Method and apparatus for transmitting scrambled data by user equipment

ABSTRACT

Provided is a data transmission system using a carrier aggregation. The data transmission system may assign a radio resource based on a correspondence relationship between a downlink and an uplink, and may transmit data using the assigned radio resource.

This application is a Continuation of U.S. patent application Ser. No.16/116,858, filed on Aug. 29, 2018, which is a Continuation of U.S.patent application Ser. No. 14/598,518 filed on Jan. 16, 2015 (now U.S.Pat. No. 10,075,276 granted on Sep. 11, 2018), which is a Divisional ofU.S. patent application Ser. No. 14/060,319 filed on Oct. 22, 2013 (nowU.S. Pat. No. 8,971,168 granted on Mar. 3, 2015), which is aContinuation of U.S. patent application Ser. No. 13/733,453 filed onJan. 3, 2013, (now U.S. Pat. No. 8,593,936 granted on Nov. 26, 2013),which is a Continuation of U.S. patent application Ser. No. 13/441,058filed on Apr. 6, 2012 (now U.S. Pat. No. 8,363,537 granted on Jan. 29,2013), which is a continuation of PCT Application No. PCT/KR2011/000195filed on Jan. 11, 2011, which claims priority to, and the benefit ofKorean Patent Application No. 10-2010-0002231 filed on Jan. 11, 2010,Korean Patent Application No. 10-2010-0009024 filed on Feb. 1, 2010,Korean Patent Application No. 10-2010-0013352 filed on Feb. 12, 2010,Korean Patent Application No. 10-2010-0030515 filed on Apr. 2, 2010,Korean Patent Application No. 10-2010-0032647 filed on Apr. 9, 2010,Korean Patent Application No. 10-2010-0076337 filed on Aug. 9, 2010,Korean Patent Application No. 10-2010-0079742 filed on Aug. 18, 2010,Korean Patent Application No. 10-2010-0083363 filed on Aug. 27, 2010,Korean Patent Application No. 10-2010-0085528 filed on Sep. 1, 2010,Korean Patent Application No. 10-2010-0085888 filed on Sep. 2, 2010,Korean Patent Application No. 10-2010-0110258 filed on Nov. 8, 2010,Korean Patent Application No. 10-2010-0111130 filed on Nov. 9, 2010,Korean Patent Application No. 10-2010-0112531 filed on Nov. 12, 2010,and Korean Patent Application No. 10-2011-0002855 filed on Jan. 11,2011, in the Korean Intellectual Property Office. The content of theaforementioned applications is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a wireless communication system, andmore specifically, to a wireless communication system employing carrieraggregation (CA).

BACKGROUND ART

A carrier aggregation (CA) scheme corresponds to technology of enhancingthe efficiency of data transmission by merging a plurality of componentcarriers. A terminal or a base station may be assigned with theplurality of component carriers and may transmit or receive data usingthe plurality of component carriers.

The terminal or the base station may transmit control informationassociated with the data. Acknowledgement/negative-acknowledgementinformation (ACK/NACK) and an amount of assigned radio resources may beused as an example of the control information. There is a desire forresearch regarding a component carrier used to transmit controlinformation among a plurality of component carriers and the controlinformation to be transmitted when the plurality of component carriersis assigned.

DISCLOSURE OF INVENTION TECHNICAL GOALS

An aspect of the present invention provides a method of transmittingcontrol information when a component carrier scheme is applied.

Technical Solutions

According to an aspect of the present invention, there is provided aterminal including: a receiver to receive control information and datausing a plurality of downlink component carriers; a controller todetermine an uplink channel element included in an uplink componentcarrier, based on an index of a channel element used to transmit thecontrol information among a plurality of downlink channel elementsincluded in the plurality of downlink component carriers; and atransmitter to transmit acknowledgement/negative-acknowledgementinformation (ACK/NACK) associated with the data using the determineduplink channel element.

According to another aspect of the present invention, there is provideda terminal including: a receiver to receive data from a base station; acontroller to generate ACK/NACK associated with the data; and atransmitter to transmit, to the base station, a data packet includingthe ACK/NACK and a scheduling request with respect to the base station.The transmitter may determine a transmit power of the data packet basedon a number of bits of the ACK/NACK and a number of bits of thescheduling request that are included in the data packet.

According to still another aspect of the present invention, there isprovided a terminal including: a receiver to receive, from a basestation, information associated with downlink component carriersavailable for a communication between the base station and the terminal,and to receive a data block using a portion of or all of data receivingcomponent carriers among the downlink component carriers; and anACK/NACK generator to generate ACK/NACK associated with the data blockwith respect to each of the downlink component carriers, based on atransmission mode of each of the downlink component carriers.

According to yet another aspect of the present invention, there isprovided a terminal including a transmitter to transmit, to a basestation, a subframe including a first slot and a second slot. A firstcyclic shift included in the first slot and a second cyclic shiftincluded in the second slot may be different from each other.

Effect of the Invention

According to embodiments of the present invention, it is possible totransmit control information when a component carrier scheme is applied.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating correspondence relationship between adownlink component carrier and an uplink component carrier;

FIG. 2 is a diagram illustrating an example of a downlink grant beingpositioned in a single component carrier;

FIG. 3 is a diagram illustrating an example of a downlink grant beingpositioned in a plurality of component carriers;

FIG. 4 is a diagram illustrating a channel structure according to anembodiment of the present invention;

FIG. 5 is a block diagram illustrating a configuration of a terminalaccording to an embodiment of the present invention;

FIG. 6 is a diagram illustrating a channel structure according toanother embodiment of the present invention;

FIG. 7 is a diagram illustrating a channel structure according to stillanother embodiment of the present invention;

FIG. 8 is a diagram illustrating a channel structure according to yetanother embodiment of the present invention;

FIG. 9 is a block diagram illustrating a configuration of a terminalaccording to another embodiment of the present invention;

FIG. 10 a block diagram illustrating a configuration of a terminalaccording to still another embodiment of the present invention;

FIG. 11 a block diagram illustrating a configuration of a terminalaccording to yet another embodiment of the present invention; and

FIG. 12 through FIG. 14 are diagrams illustrating an example of adiscrete Fourier transform (DFT)-S-orthogonal frequency divisionmultiplexing (OFDM) based transmission.

BEST MODE FOR CARRYING OUT THE INVENTION

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. The embodiments are described below in order to explain thepresent invention by referring to the figures.

FIG. 1 is a diagram illustrating correspondence relationship between adownlink component carrier (CC) and an uplink CC.

A terminal may receive data from a base station using a plurality ofdownlink CCs 110, 120, and 130, and may transmit, to the base station,an acknowledgement (ACK)/negative-acknowledgement (NACK) message withrespect to the data using a plurality uplink CCs 140 and 150.

Each of the downlink CCs 110, 120, and 130 may include controlinformation, for example, Physical Downlink Control Channels (PDCCHs)111, 121, and 131, and data, for example, Physical Downlink SharedChannels (PDSCHs) 112, 122, and 132.

Each of the uplink CCs 140 and 150 may include control information, forexample, Physical Uplink Control Channels (PUCCHs) 141, 143, 151, and153, and data, for example, Physical Uplink Shared Channels (PUSCHs) 142and 152.

The terminal may set, as the downlink primary component carrier (PCC),one of CCs included in a set of configured CCs. Remaining CCs excludingthe downlink PCC from the configured CCs may be referred to as downlinksecondary component carriers (SCCs).

The downlink PCC may be included in the set of configured CCs of theterminal at all times while the terminal maintains an access with thebase station. The downlink PCC may correspond to a CC used at the basestation to transmit system information. The base station may transmitsystem information associated with the PCC and system informationassociated with the SCC using the PCC.

The base station may notify the terminal of the downlink PCC using RadioResource Control (RRC) signaling.

An uplink CC used at the terminal to transmit PUCCHacknowledgement/negative-acknowledgement information (ACK/NACK) may bereferred to as the uplink PCC. The downlink PCC and the uplink PCC mayneed to be connected to each other by a predetermined connectionrelationship. The base station may notify the terminal of the uplink PCCusing RRC signaling.

The uplink PCC and the downlink PCC may be differently set for eachterminal.

Using RRC signaling, the base station may notify the terminal regardingwhether cross-carrier scheduling is to be employed. When thecross-carrier scheduling is not used, scheduling information orassignment information of the PDSCHs 112, 122, and 132 included in thedownlink CCs 110, 120, and 130 may be transmitted using the PDCCHs 111,121, and 131 included in the corresponding downlink CCs 110, 120, and130. Specifically, scheduling information or assignment information ofthe PDSCH 112 included in the downlink CC 110 may be transmitted usingonly the PDCCH 111 included in the downlink CC 110. Schedulinginformation or assignment information of the PDSCH 122 included in thedownlink CC 120 may be transmitted using only the PDCCH 121 included inthe downlink CC 120.

Considering uplink scheduling, a PDCCH included in a downlink CC mayinclude scheduling information associated with a PUSCH of an uplink CCcorresponding to the downlink CC.

The base station may transmit, to the terminal, information associatedwith correspondence relationship between an uplink CC and a downlink CC.Based on the correspondence relationship between CCs, the terminal maybe aware of that a PDCCH is associated with scheduling of a PUSCHincluded in which uplink CC. Referring to FIG. 1 , the downlink CC 110corresponds to the uplink CC 140, and the downlink CC 120 corresponds tothe uplink CC 150. In this case, scheduling information included in thePDCCH 111 may relate to the PUSCH 142, and scheduling informationincluded in the PDCCH 121 may relate to the PUSCH 152.

The base station may include, in system information, the correspondencerelationship between the CCs and thereby transmit the systeminformation.

FIG. 2 is a diagram illustrating an example of downlink grants beingpositioned in a single CC. The downlink grants may be transmitted via aPDCCH and may include resource assignment information associated withdownlink or uplink.

When using cross-carrier scheduling, scheduling information orassignment information of each PDSCH may be transmitted using a PDCCH ofa predetermined downlink CC. In this case, the downlink CC including thePDCCH used to transmit scheduling information may correspond to the PCC.

An uplink ACK/NACK resource may be determined based on an index value ofa first channel element among Control Channel Elements (CCEs)constituting the PDCCH used for the downlink grant. When data istransmitted to a plurality of CCs, the same number of PDCCHs as a numberof the plurality of CCs may be used.

Accordingly, when a total of N PDCCHs are used, a total of N ACK/NACKresources may be determined to be mapped by an index value of a firstchannel element of each PDCCH. The terminal may transmit an ACK/NACKsignal using N ACK/NACK resources. The terminal may also transmitACK/NACK by assigning an additional radio resource to an uplink PCC.

The terminal may transmit N ACK/NACK signals using a predeterminedsingle uplink CC. As shown in FIG. 2 , when a PDCCH is transmitted usingonly a downlink PCC, implicit resource mapping relationship of aconventional Long Term Evolution (LTE) Release 8/9 standard may beemployed as is and thus, resources may be efficiently used.

FIG. 3 is a diagram illustrating an example of downlink grants beingpositioned in a plurality of CCs. Referring to FIG. 3 , PDCCHs may betransmitted using a plurality of downlink CCs. However, ACK/NACK may betransmitted using a single uplink CC. Accordingly, a resourcecorresponding to an uplink PCC may be set with respect to a PDCCHpresent in each corresponding downlink CC.

Also, ACK/NACK may be transmitted by assigning an additional radioresource to the uplink PCC.

When cross-carrier scheduling is set with respect to the terminal, acarrier indicator field (CIF) within the PDCCH may be used. When thePDCCH is received using only the downlink PCC as shown in FIG. 2 , theterminal may transmit ACK/NACK by selecting a resource or a sequenceusing PUCCH format 1a or format 1b ACK/NACK resources that aredetermined within the uplink PCC, based on implicit mapping relationshipbetween ACK/NACK resources and the lowest CCE index of the PDCCH asdefined in the ITE Release 8 standard. In particular, when the terminalis configured to use two downlink CCs, that is, when two downlinkconfigured CCs are present, and when cross-carrier scheduling is setwith respect to the terminal, the PDCCH may be received using only thedownlink PCC at all times as shown in FIG. 2 .

Even though PDSCH assignment using a dynamic PDCCH is absent in the PCC,semi-persistent scheduling (SPS) assignment may be present in the PCC.In this case, the terminal may include a persistent ACK/NACK resourcecorresponding to the SPS assignment in ACK/NACK channels for resourceand sequence selection.

However, when all of downlink CCs are connected to the same singleuplink CC, the resource and sequence selection may be performed using anuplink ACK/NACK channel that is secured based on implicit mappingrelationship between a lowest CCE index of the PDCCH and the ACK/NACKresource, regardless of whether the cross-carrier scheduling is set withrespect to the terminal.

When a resource is secured according to the aforementioned scheme, anadditional resource may need to be secured in order to enhance theperformance of ACK/NACK transmission.

According to an aspect, an uplink ACK/NACK resource may be secured byemploying the implicit mapping relationship of the ACK/NACK resourcedisclosed in the LTE Rel-8/9 standard, and by substituting the secondlowest CCE index of the PDCCH instead of substituting the lowest CCEindex. In this case, the base station may need to constitute the PDCCHwith minimum two CCEs.

However, in the above scheme, when an SPS is assigned to a subframe, anassigned downlink PDCCH may be absent in the subframe. In this case,since only a single ACK/NACK resource corresponding to the SPSassignment is secured in LTE, another assignment scheme may need to beemployed to secure an additional resource.

According to an aspect, an additional resource may be secured usingexplicit signaling. As an example of the explicit signaling, theterminal may be directly notified through RRC signaling, or may benotified by assigning a single bit or a plurality of bits to a DCI(downlink control information) format for downlink scheduling. Asanother example, the terminal may be notified of a resource by notifyingthe terminal of a portion of a resource assignment position through RRCsignaling, and by finally assigning the single bit or the plurality ofbits to the DCI format for downlink scheduling.

When cross-carrier scheduling is not set with respect to the terminal, aPDCCH may not include the CIF. In this case, the base station may assignan ACK/NACK resource within the uplink PCC through separate RRCsignaling. Here, a number of ACK/NACK resources corresponding to anumber of downlink configured CCs may need to be assigned. For example,when the number of downlink configured CCs is N, N PUCCH ACK/NACKresources may need to be assigned. When a PDSCH assignment using adynamic PDCCH is present in the downlink PCC, an ACK/NACK resourcedetermined within the uplink PCC based on implicit mapping relationshipbetween the ACK/NACK resource and the lowest CCE index defined in theLTE Release 8 standard may be included in ACK/NACK channels for theresource and sequence selection.

Even though the PDSCH assignment using the dynamic PDCCH is absent inthe downlink PCC, the SPS assignment may be present in the downlink PCC.In this case, a persistent ACK/NACK resource corresponding to the SPSassignment may be included in ACK/NACK channels for the resource andsequence selection.

The aforementioned scheme may be applicable when different uplink CCsare connected to a single downlink CC. When all of downlink CCs areconnected to the same uplink CC, the resource and sequence selection maybe always performed using the uplink ACK/NACK channel that is securedbased on implicit mapping relationship between the ACK/NACK resource ofthe PDCCH and the lowest CCE index defined in the LTE Release 8/9standard, regardless of whether cross-carrier scheduling is set withrespect to the terminal.

According to an aspect, with respect to all of downlink CCs connected tothe uplink PCC, the uplink ACK/NACK channel secured based on theimplicit mapping relationship defined in the LTE Release 8/9 standardmay be included in the ACK/NACK channel for the resource and sequenceselection at all times. Even in this case, when the PDSCH assignmentusing the dynamic PDCCH is absent, however, the SPS assignment ispresent with respect to the downlink CCs connected to the uplink PCC,the persistent ACK/NACK resource corresponding to the SPS assignment maybe included in ACK/NACK channels for the resource and sequenceselection.

When cross-carrier scheduling is not set with respect to the terminal,the PDCCH may not include the CIF. Even in this case, an additionalresource may be further secured and be included in ACK/NACK channels forthe resource and sequence selection.

When a PDCCH is transmitted from the downlink PCC with respect to anuplink PCC whereby resource assignment is performed, an uplink ACK/NACKresource may be secured by employing implicit mapping relationship ofthe ACK/NACK resource disclosed in the LTE Release 8/9 standard, and bysubstituting the second lowest CCE index of the PDCCH, instead ofsubstituting the lowest CCE index of the PDCCH. In this case, the basestation may constitute the PDCCH with minimum two CCEs. However, in thisscheme, when an SPS is assigned to a subframe, an assigned downlinkPDCCH may be absent in the subframe. In this case, since only a singleACK/NACK resource corresponding to the SPS assignment is secured in LTE,another assignment scheme may need to be employed to secure anadditional resource. The additional resource may be secured usingexplicit signaling. The above scheme may directly notify the terminalthrough RRC signaling, or may notify the terminal by assigning a singlebit or a plurality of bits to a DCI format for downlink scheduling. Asanother scheme, the terminal may be notified of a resource by notifyingthe terminal of a portion of a resource assignment position through RRCsignaling and by finally assigning the single bit or the plurality ofbits to the DCI format for downlink scheduling.

Hereinafter, a resource assignment method for ACK/NACK feedback using achannel selection scheme will be described using examples. It may beassumed that a number of channels are assigned based on a number of bitsof ACK/NACK to be transmitted as shown in Table 1.

TABLE 1 Number of channels assigned based on number of bits of ACK/NACKNumber of Maximum number of A/N channels A/N bits required for channelselection 2 2 3 3 4 4

For channel selection, when a PDSCH assignment is performed using aPDCCH, minimum at least one channel may be secured from indices of CCEsconstituting the PDCCH, ACK/NACK resource indication (ARI) information,and the like. When a number of transport blocks is one, a single channelmay be secured. When the number of transport blocks is two, two channelsmay be secured.

When the PDCCH is transmitted from the downlink PCC and is used for dataassignment with respect to the downlink PCC or a downlink SCC, and whena single transport block is transmitted, a single channel may be securedaccording to the Rel-8/9 resource assignment method using the lowest CCEindex among indices of CCEs constituting the PDCCH. When two transportblocks are transmitted, two channels may be secured according to theRel-8/9 resource assignment method using the lowest CCE index and thesecond lowest CCE index among indices of the CCEs constituting thePDCCH.

When the PDCCH is transmitted from the downlink PCC and a singletransport block is transmitted, assignment of an additional resource maybe required so that the terminal using multiple antennas may performtransmission using a Spatial Orthogonal Resource Transmit Diversity(SORTD). In this case, two channels may be secured according to theRel-8/9 resource assignment method using the lowest CCE index and thesecond lowest CCE index among indices of the CCEs constituting thePDCCH.

According to another aspect, when a PDCCH is transmitted from an SCCinstead of a downlink PCC, a channel may be secured according to thefollowing scheme. The base station may notify the terminal of aparameter n_(PUCCH,0) ⁽¹⁾ through RRC signaling. When the PDCCH istransmitted from the SCC instead of the downlink PCC, 2 bits within aDCI format may be used as resource assignment information. The above 2bits may correspond to ARI. When a plurality of PDCCHs is transmittedfrom the SCC, all ARI may use the same value. The ARI may map n_(ARI)value, and may define n_(PUCCH) ⁽¹⁾ as follows:n _(PUCCH) ⁽¹⁾ =n _(PUCCH,0) ⁽¹⁾ +n _(ARI)

For example, n_(ARI) value according to an ARI bit value may be definedas shown in Table 2. Δ_(offset) may use a value predetermined in astandard, or may use a value notified from the base station to theterminal through higher layer signaling.

TABLE 2 n_(ARI) value according to ARI bit value ARI n_(ARI) 00 0 01 1Δ_(offset) 10 2 Δ_(offset) 11 3 Δ_(offset)

The terminal may determine a usage resource from n_(PUCCH) ⁽¹⁾ using thesame scheme as Rel-8/9. When a single transport block is transmitted, asingle channel determined according to the above scheme may be secured.When two transport blocks are transmitted, one method is that theterminal may use two resources corresponding to n_(PUCCH) ⁽¹⁾, n_(PUCCH)⁽¹⁾+1.

According to another aspect, when an SCC transmitting a PDCCH containingdownlink scheduling information is set to a transmission mode capable oftransmitting maximum two transport blocks, the base station maytransmit, to the terminal using RRC signaling, four pairs of candidatevalues of n_(PUCCH) ⁽¹⁾ with respect to the SCC. Also, when the basestation selects a single pair from the four pairs based on an ARIincluded in DCI and an actual number of transport blocks are two, theterminal may use the selected resource pair for the channel selection.When the number of actual transport blocks is single, the terminal mayuse the first resource in the selected resource pair for the channelselection.

Even though a single transport block is transmitted for transmission ofthe terminal using multiple antennas using SORTD, the assignment of anadditional resource may be required. In this case, two channelscorresponding to n_(PUCCH) ⁽¹⁾, n_(PUCCH) ⁽¹⁾+1 may be secured for thechannel selection.

A number of ACK/NACK bits to be transmitted by the terminal may bedetermined based on a number of configured CCs for the terminaltransmission mode of each configured CC. That is, 2 bits may be used fora CC set to the transmission mode capable of transmitting maximum twotransport blocks, and a single bit may be used for a CC set to thetransmission mode capable of transmitting a maximum single transportblock. When N corresponds to a total number of ACK/NACK bits to betransmitted by the terminal,

$N = {\sum\limits_{i = 1}^{C_{N}}{Q_{i}.}}$Here, Q_(i) denotes a number of A/N bits with respect to an i^(th)configured CC, and C_(N) denotes the number of configured CCs for theterminal.

Two bits of ACK/NACK transmission occurs when the downlink PCC (orPCell) and a single SCC (or SCell) are configured and each is set to thetransmission mode capable of transmitting maximum one transport block.

TABLE 3 bit assignment when 2 bits of A/N transmission occurs A/N bitassignment PCell SCell_0 Case 1 1 bit 1 bit

In this case, when the terminal does not use the SORTD, ACK/NACKchannels required may be secured through the aforementioned scheme andbe used for the channel selection. When the terminal uses the SORTD, twochannels may be secured for each CC where a PDCCH occurs through theaforementioned scheme and thus, may be used for the channel selectionand the SORTD transmission.

When 3 bits of ACK/NACK transmission occurs, three cases may be probableas shown in Table 4.

TABLE 4 bit assigment when 3 bits of A/N transmission occurs A/N bitassignment PCell SCell_0 SCell_1 Case 1 1 bit 1 bit 1 bit Case 2 2 bits1 bit Case 3 1 bit 2 bits

When the terminal uses SORTD, case 1 of Table 4 may secure two channelsfor each CC where a PDCCH occurs through the aforementioned scheme andthus, may use the secured channels for the channel selection and theSORTD transmission.

When the PDCCH occurs only in PCell, case 2 of Table 4 may secure atotal of two channels. Accordingly, two channels may need to beadditionally secured so that the terminal may use the SORTD. When thePDCCH occurs in both PCell and SCell, a total of four channels may besecured and thus, a remaining single channel may be used for the SORTDtransmission. Specifically, the SORTD transmission may be performedusing a single channel obtained as a result of the channel selection,and a remaining single channel. When the PDCCH occurs only in SCell, atotal of two channels may be secured and thus, the SORTD transmissionmay be performed.

Case 3 of Table 4 may be similar to case 2. Here, a position of PCelland a position of SCell may be switched.

When 4 bits of ACK/NACK transmission occurs, four cases may be probableas shown in Table 5.

TABLE 5 bit assignment when 4 bits of A/N transmission occurs A/N bitassignment PCell SCell_0 SCell_1 SCell_2 Case 1 1 bit 1 bit 1 bit 1 bitCase 2 2 bits 1 bit 1 bit Case 3 1 bit 2 bits 1 bit Case 4 2 bits 2 bits

When the terminal uses SORTD, case 1 of Table 5 may secure two channelsfor each CC where a PDCCH occurs through the aforementioned scheme andthus, may use the secured channels for the channel selection and theSORTD transmission.

When the PDCCH occurs in all of CCs, case 2 of Table 5 may secure atotal of six channels. Accordingly, four channels may be used for thechannel selection. The terminal may perform the SORTD transmission byselecting a single channel from remaining two channels. Specifically,the terminal may perform the SORTD transmission using a single channelobtained as a result of the channel selection and another channel amongthe remaining two channels, which is pre-defined in the standard.

When the PDCCH occurs in all of CCs, case 3 of Table 5 may secure atotal of six channels. Accordingly, four channels may be used for thechannel selection. The terminal may perform the SORTD transmission byselecting a single channel from remaining two channels. Specifically,the terminal may perform the SORTD transmission using a single channelobtained as a result of the channel selection and another channel amongthe remaining two channels, which is pre-defined in the standard.

Case 4 of Table 5 may secure a total of four channels and thus, mayperform the channel selection using the four channels. The SORTDtransmission may not be allowed.

It may be difficult for the terminal using a discrete Fourier transform(DFT)-S-orthogonal frequency division multiplexing (OFDM) basedtransmission method to perform code division multiplexing (CDM) withrespect to a resource block with other terminals using a PUCCH resourcedefined in LTE Rel-8/9. Accordingly, an ACK/NACK resource within anuplink PCC may be separately assigned through RRC signaling. The aboveresource may be referred to as a carrier aggregation (CA) PUCCH ACK/NACKresource. An assignment position of the CA PUCCH ACK/NACK resource maybe within an area for existing Rel-8/9 PUCCH channel quality information(CQI), persistent ACK/NACK, and a scheduling request resource, and maynot fringe a dynamic ACK/NACK resource area mapped by the lowest CCEindex of the PDCCH. When the CA PUCCH ACK/NACK resource fringes thedynamic ACK/NACK resource area, the terminal may collide with anotherterminal using the dynamic ACK/NACK resource. The base station maynotify the terminal of a time-domain sequence and a position of a radioresource block used at the terminal.

According to an aspect, the base station may notify the terminal of aradio resource by notifying the terminal of a portion of a resourceassignment position through RRC signaling, and by finally assigning asingle bit or a plurality of bits to a DCI format for downlinkscheduling.

Regardless of the above transmission scheme, when the terminal receivesa downlink assignment with respect to only a single downlink CC in asubframe and when the assigned CC is the downlink PCC, the terminal maybe assigned with an ACK/NACK resource using the same scheme as LTERel-8/9, and may perform transmission using the same transmission schemeas LTE Rel-8/9.

Even though a PDSCH assignment using a dynamic PDCCH is absent in thedownlink PCC, an SPS assignment may be present in the PCC. In this case,the terminal may use a persistent ACK/NACK resource corresponding to theSPS assignment and may perform transmission using the same transmissionscheme as LTE Rel-8/9.

Hereinafter, a resource assignment when ACK/NACK feedback is performedbased on DFT-S-OFDM will be described.

When a normal cyclic prefix (CP) is used, a structure of having tworeference signals per slot as shown in a part (A) of FIG. 6 may be used.When an extended CP is used, a structure of having a single referencesignal per slot as shown in a part (B) of FIG. 7 may be used.

When the extended CP is used, a position of a reference signal may be BL#3. In a subframe where a sounding reference signal (SRS) is nottransmitted, when the normal CP is used, maximum five terminals may bemultiplexed to a single resource block. When the extended CP is used,maximum four terminals may be multiplexed to a single resource block.

In a subframe where the SRS is transmitted, the last symbol of thesecond slot may not be transmitted. Accordingly, in the subframe wherethe SRS is transmitted, when the normal CP is used, maximum fourterminals may be multiplexed to a single resource block. When theextended CP is used, maximum three terminals may be multiplexed to asingle resource block.

The base station may notify the terminal of parameter n_(PUCCH,0) ⁽³⁾through RRC signaling. When a PDCCH is transmitted from an SCC, 2 bitswithin a DCI format may be used as resource assignment information. Theabove 2 bits may be referred to as ARI. When a plurality of PDCCHs istransmitted from the SCC, all of ARI may use the same value. The ARI maymap n_(ARI) value and may define n_(PUCCH) ⁽³⁾ as follows.n _(PUCCH) ⁽³⁾ =n _(PUCCH,0) ⁽³⁾ +n _(ARI)

For example, n_(ARI) value according to an ARI bit value may be definedas shown in Table 6. Δ_(offset) may use a value predetermined in thestandard, or may use a value notified from the base station to theterminal through higher layer signaling.

TABLE 6 n_(ARI) value according to ARI bit value ARI n_(ARI) 00 0 01 1Δ_(offset) 10 2 Δ_(offset) 11 3 Δ_(offset)

According to another aspect, the base station may perform RRC signalingof four candidate values of n_(PUCCH) ⁽³⁾ with respect to the terminal,and may select one candidate value from the four candidate values basedon ARI included in a DCI.

The terminal may determine, from n_(PUCCH) ⁽³⁾, a position of a physicalresource block (PRB) and a time-domain orthogonal sequence to be used. Aresource to be used by the terminal may be indicated as the followingtwo resource indices.

n_(PRB): PRB index

N_(OC): time-domain orthogonal sequence index

n_(PRB) may be obtained from the same equation as Rel-8/9, as follows:

$n_{PRB} = \left\{ {{\begin{matrix}\left\lfloor \frac{m}{2} \right\rfloor \\{N_{RB}^{UL} - 1 - \left\lfloor \frac{m}{2} \right\rfloor}\end{matrix}\begin{matrix}{\;{{{if}\mspace{14mu}\left( {m + {n_{s}{{mod}2}}} \right){{mod}2}} = 0}} \\{{{if}\mspace{14mu}\left( {m + {n_{s}{{mod}2}}} \right){{mod}2}} = 1}\end{matrix}},} \right.$

1) First method for assigning a radio resource:

Initially, new parameters may be defined as follows:

N_(SF,1): may have a value of 4 or 5 as the spreading factor of slot #1corresponding to the second slot.

N_(RB) ⁽³⁾: RB offset for DFT-S-OFDM A/N resource

m and n_(oc) may be obtained according to the following equations.m=└n _(PUCCH) ⁽³⁾ /N _(SF,1) ┘+N _(RB) ⁽³⁾.n _(sc) =n _(PUCCH) ⁽³⁾mod N _(SF,1)

When the terminal using multiple antennas performs transmission usingSORTD, two resources may need to be assigned. For this, the base stationmay notify the terminal of parameters n_(PUCCH,0) ⁽³⁾ and n_(PUCCH,1)⁽³⁾ through RRC signaling. n_(PUCCH,SORTD0) ⁽³⁾ and n_(PUCCH,SORTD1) ⁽³⁾may be determined by n_(PUCCH,1) ⁽³⁾ and n_(ARI) as follows:n _(PUCCH,SORTD0) ⁽³⁾ =n _(PUCCH,0) ⁽³⁾ +n _(ARI)n _(PUCCH,SORTD1) ⁽³⁾ =n _(PUCCH,1) ⁽³⁾ +n _(ARI)

The terminal may use two resources that may be obtained using the samemethod as the aforementioned single resource assignment, that is, amethod of substituting n_(PUCCH,SORTD0) ⁽³⁾ and n_(PUCCH,SORTD1) ⁽³⁾instead of n_(PUCCH) ⁽³⁾ used for the single resource assignment.Specifically, a single antenna port may be transmitted using a resourceobtained with n_(PUCCH,SORTD0) ⁽³⁾, and another antenna port may betransmitted using a resource obtained with n_(PUCCH,SORTD1) ⁽³⁾.

As another method, the base station may transmit, to the terminal, fourpairs of candidate values of n_(PUCCH,SORTD0) ⁽³⁾ and n_(PUCCH,SORTD1)⁽³⁾ through RRC signaling, and may select a single pair from the fourpairs based on ARI included in DCI.

Decision of demodulation reference signal sequence: The terminal maydetermine, from n_(oc), a cyclic shift of a demodulation referencesignal sequence to be used by the terminal.

In a case where N_(SF,1)=5, when n_(s) mod 2=0, n′(n_(s))=(3n_(oc))modN_(sc) ^(RB). Here, n_(s) denotes a slot number.

In a case where N_(SF,1)=, when n_(s) mod 2=0, n′(n_(s)) may bedetermined from the following Table 7. Through signaling, the basestation may notify the terminal in advance of which case of Table 1 isbeing used. As another method, when deltaPUCCH-Shift Δ_(shift)^(PUCCH)=3, case 2 may be used and otherwise, case 1 may be used. Here,deltaPUCCH-Shift Δ_(shift) ^(PUCCH) denotes a parameter indicating acyclic shift interval in PUCCH format 1/1a/1b.

TABLE 7 decision of demodulation reference signal sequence according ton_(oc) value n_(oc) Case 1: n′ (n_(s)) Case 2: n′ (n_(s)) 0 0 0 1 3 3 26 6 3 8 9 4 10

When n_(s) mod 2=1 n′(n_(s)) may be determined according to thefollowing equation regardless of N_(SF,1).n′(n _(s))=[N _(sc) ^(RB)(n′(n _(s)−1)+1))]mod(N _(sc) ^(RB)+1)−1

Using the same method as Rel-8/9, cyclic shift α(n_(s),l) used by theterminal may be determined as follows:α(n _(s) ,l)=2π·n _(cs)(n _(s) ,l)/N _(sc) ^(RB)n _(cs)(n _(s) ,l)=(n _(cs) ^(cell)(n _(s) ,l)+n′(n _(s)))mod N _(SC)^(RB)

2) Second Method for Assigning a Radio Resource:

Initially, new parameters may be defined as follows:

N_(MF): multiplexing factor

N_(SF,1): spreading factor of slot #0 corresponding to a first slot

N_(SF,0): spreading factor of slot #1 corresponding to a second slot

$N_{MF} = {\min\left( {N_{{SF},1},\left\lfloor \frac{N_{sc}^{RB}}{\Delta_{shift}^{PUCCH}} \right\rfloor} \right)}$

N_(RB) ⁽³⁾: RB offset for DFT-S-OFDM A/N resource

m and n_(oc) may be calculated according to the following equations.m=└n _(PUCCH) ⁽³⁾ /N _(SF,0) ┘+N _(RB) ⁽³⁾.n _(oc) =n _(PUCCH) ⁽³⁾mod N _(MF).

When the terminal using multiple antennas employs SORTD, two resourcesmay need to be assigned. In this case, the base station may notify theterminal of parameters n_(PUCCH,0) ⁽³⁾ and n_(PUCCH,1) ⁽³⁾ through RRCsignaling. n_(PUCCH,SORTD0) ⁽³⁾ and n_(PUCCH,SORTD1) ⁽³⁾ may bedetermined by n_(PUCCH,1) ⁽³⁾ and n_(ARI) as follows:n _(PUCCH,SORTD0) ⁽³⁾ =n _(PUCCH,0) ⁽³⁾ +N _(ARI)n _(PUCCH,SORTD1) ⁽³⁾ =n _(PUCCH,1) ⁽³⁾ +n _(ARI)

The terminal may use two resources that may be obtained using the samemethod as the aforementioned single resource assignment, that is, amethod of substituting n_(PUCCH,SORTD0) ⁽³⁾ and n_(PUCCH,SORTD1) ⁽³⁾instead of n_(PUCCH) ⁽³⁾ used for the single resource assignment.Specifically, a single antenna port may be transmitted using a resourceobtained with n_(PUCCH,SORTD0) ⁽³⁾, and another antenna port may betransmitted using a resource obtained with n_(PUCCH,SORTD1) ⁽³⁾.

As another method, the base station may transmit, to the terminal, fourpairs of candidate values of n_(PUCCH,SORTD0) ⁽³⁾ and n_(PUCCH,SORTD1)⁽³⁾ through RRC signaling, and may select a single pair form the fourpairs based on ARI included in DCI.

Decision of demodulation reference signal sequence: The terminal maydetermine, from n_(c), a cyclic shift of a demodulation reference signalsequence to be used by the terminal.

When n_(s) mod 2=0 n′(n_(s)) may be determined with respect to each ofN_(MF)=4 and N_(MF)=5 according to the following Table 8.

TABLE 8 decision of demodulation reference signal sequence n′ (n_(s))n_(oc) N_(MF) = 5 N_(MF) = 4 0 0 0 1 6 6 2 3 3 3 8 9 4 10 N.A.

Instead of Table 8, Table 9 may be employed. Compared to Table 8, Table9 assigns n_(oc) while sequentially increasing n_(oc). Accordingly, whena small number of terminals are assigned, a cyclic shift interval of thedemodulation reference sequence may be maintained to be great.

TABLE 9 decision of demodulation reference signal sequence n′ (n_(s))n_(oc) N_(MF) = 5 N_(MF) = 4 0 0 0 1 3 3 2 6 6 3 8 9 4 10 N.A.

When n_(s) mod 2=1 n′(n_(s)) may be determined according to thefollowing equation.n′(n _(s))=[N _(sc) ^(RB)(n′(n _(s)−1)+1))]mod(N _(sc) ^(RB)+1)−1

Using the same method as Rel-8/9, cyclic shift α(n_(s),l) used by theterminal may be determined as follows.α(n _(s) ,l)=2π·n _(cs)(n _(s) ,l)/N _(sc) ^(RB)n _(cs)(n _(s) ,l)=(n _(cs) ^(cell)(n _(s) ,l)+n′(n _(s)))mod N _(SC)^(RB)

3) Third Method for Assigning Radio Resource:

Initially, new parameters may be defined as follows:

N_(MF,0): multiplexing factor of the first slot

N_(MF,1): multiplexing factor of the second slot

N_(SF,1): spreading factor of the first slot

N_(SF,0): spreading factor of the second slot

$N_{{MF},0} = {\min\left( {N_{{SF},0},\left\lfloor \frac{N_{sc}^{RB}}{\Delta_{shift}^{PUCCH}} \right\rfloor} \right)}$$N_{{MF},1} = {\min\left( {N_{{SF},1},\left\lfloor \frac{N_{sc}^{RB}}{\Delta_{shift}^{PUCCH}} \right\rfloor} \right)}$

N_(RB) ⁽³⁾: RB offset for DFT-S-OFDM A/N resource

PRB index m may be calculated according to the following equation.m=└n _(PUCCH) ⁽³⁾ /N _(MF,0) ┘+N _(RB) ⁽³⁾.

An advantage of the above scheme lies in that a resource area may be setbased on N_(MF,0) corresponding to an actual multiplexing capability ofthe normal format.

A time-domain sequence index n_(oc,0) of the first slot may becalculated according to the following equation.n _(oc,0) g=n _(PUCCH) ⁽³⁾mod N _(MF,1)

The following equation may also be employed.n _(oc,0)=(n _(PUCCH) ⁽³⁾mod N _(MF,0))mod N _(MF,1)

A time-domain sequence index n_(oc,1) of the second slot may apply slotlevel remapping.

When the terminal using multiple antennas employs SORTD, two resourcesmay need to be assigned. For this, the base station may notify theterminal of parameters n_(PUCCH,0) ⁽³⁾ and n_(PUCCH,1) ⁽³⁾ through RRCsignaling. n_(PUCCH,SORTD0) ⁽³⁾ and n_(PUCCH,SORTD1) ⁽³⁾ may bedetermined by n_(PUCCH,1) ⁽³⁾ and n_(ARI) as follows:n _(PUCCH,SORTD0) ⁽³⁾ =n _(PUCCH,0) ⁽³⁾ +N _(ARI)n _(PUCCH,SORTD1) ⁽³⁾ =n _(PUCCH,1) ⁽³⁾ +n _(ARI)

The terminal may use two resources that may be obtained using the samemethod as the aforementioned single resource assignment, that is, amethod of substituting n_(PUCCH,SORTD0) ⁽³⁾ and n_(PUCCH,SORTD1) ⁽³⁾instead of n_(PUCCH) ⁽³⁾ used for the single resource assignment.Specifically, a single antenna port may be transmitted using a resourceobtained with n_(PUCCH,SORTD0) ⁽³⁾, and another antenna port may betransmitted using a resource obtained with n_(PUCCH,SORTD1) ⁽³⁾.

As another method, the base station may transmit, to the terminal, fourpairs of candidate values of n_(PUCCH,SORTD0) ⁽³⁾ and n_(PUCCH,SORTD1)⁽³⁾ through RRC signaling, and may select a single pair form the fourpairs based on ARI included in DCI.

Decision of demodulation reference signal sequence: A cyclic shift of ademodulation reference signal to be used by the terminal may bedetermined from n_(oc,0). Using a method similar to Rel-8/9, a cyclicshift α(n_(s),l) used by the terminal may be determined as follows:α(n _(s) ,l)=2π·n _(cs)(n _(s) ,l)/N _(sc) ^(RB)n _(cs)(n _(s) ,l)=(n _(cs) ^(cell)(n _(s) ,l)+n′(n _(s)))mod N _(SC)^(RB)

In the case of normal CP: Since a single slot includes two referencesignal blocks l=1 (BL #1) and l=5 (BL #5), n′(n_(s),l) assigned from afirst reference signal block may be set to be changed in a secondreference block. This is to enable code division multiplexed terminalsto randomize mutual interference.

When l=1, n′(n_(s),l) may be determined according to Table 10.

TABLE 10 n′ (n_(s), l) n_(oc) N_(MF,1) = 5 N_(MF,1) = 4 0 0 0 1 6 6 2 33 3 8 9 4 10 N.A.

Instead of employing Table 10, one of Table 11 and Table 12 may beemployed.

TABLE 11 n′ (n_(s), l) n_(oc) N_(MF,1) = 5 N_(MF,1) = 4 0 0 0 1 3 3 2 66 3 8 9 4 10 N.A.

TABLE 12 n′ (n_(s), l) n_(oc) N_(MF,1) = 5 N_(MF,1) = 4 0 0 0 1 3 3 2 56 3 8 9 4 10 N.A.

When l=5 n′(n_(s),l) may be expressed according to the followingequation.n′(n _(s) ,l)=[N _(sc) ^(RB)(n′(n _(s) ,l)+1)]mod(N _(sc) ^(RB)+1)−1

In the case of extended CP: A single slot may include a single referencesignal block 1=3 (BL #3). n′(n_(s),l) assigned from a reference signalblock belonging to a first slot may be set to be changed in a referenceblock belonging to a second slot. This is to enable code divisionmultiplexed terminals to randomize mutual interference.

When l=3 and n_(s) mod 2=0 n′(n_(s),l) may be expressed according toTable 11 or Table 12.

When l=3 and n_(s) mod 2=1 n′(n_(s),l) may be expressed according to thefollowing equation.n′(n _(s) ,l)=[N _(sc) ^(RB)(n′(n _(s)−1,3)+1)]mod(N _(sc) ^(RB)+1)−1

According to the 3^(rd) Generation Partnership Project (3GPP) LTERelease 8 standard, a PUCCH transmission format for transmission ofuplink control information may follow as:

Format 1/1a/1b: SR, ACK/NACK

Format 2/2a/2b: CQI, CQI+ACK/NACK

Due to the following reasons, transmission of uplink control information(UCI) of an LTE-Advanced (Release 10 and following Release) system mayneed a change:

First, using a plurality of carriers

Second, applying enhanced Multiple Input Multiple Output (MIMO)technology and Coordinated Multi-Point (CoMP) technology.

Due to the above reasons, there is a need to increase UCI payload.

Hereinafter, a method of generating, by the terminal, and transmittingan ACK/NACK signal corresponding to a plurality of CCs will bedescribed.

Method 1—method of selecting a carrier level resource and therebyperforming transmission:

For example, the above method may correspond to a case where a datatransmission is performed through two downlink CCs and a correspondinggrant channel is transmitted to each of the downlink CCs. Here, uplinkCCs corresponding to the respective downlink CCs may be predetermined.

When each downlink CC transmits a single transport block, the terminalmay need to transmit an ACK/NACK signal with respect to two transportblocks. Two uplink CCs corresponding to two downlink CCs may be present.To transmit the ACK/NACK signal corresponding to two transport blocks,the terminal may transmit a signal capable of identifying informationcorresponding to 2 bits. The terminal may transmit, to the base station,information corresponding to a total of 2 bits through selection of anuplink CC and a binary phase shift keying (BPSK) signal transmission inthe selected uplink CC. For example, when a signal transmission CC isselected from UL-CCO0 and UL-CC1 as shown in Table 13 and a BPSKmodulation is performed, the terminal may transmit a signalcorresponding to 2 bits. The base station may identify information bydetecting the uplink CC from which the signal is transmitted, and bydetecting a transmission symbol.

TABLE 13 ACK/NACK signal trans- transmission bit value mission CC symbol00 UL-CC0 0 01 UL-CC0 1 10 UL-CC1 0 11 UL-CC1 1

An advantage of the above scheme lies in that the cubic metric (CM)increase does not occur. In general, a terminal positioned at a cellboundary may have some constraints in transmit power and thus, the abovescheme may be advantageous in securing the coverage.

As another method, a method of transmitting 2-bit information through aquadrature phase shift keying (QPSK) modulation using a single CC may beemployed. However, this scheme may need an increase in a transmit powerby about 3 dB, that is, about twice in order to show the sameperformance as the aforementioned scheme.

Hereinafter, a method of transmitting ACK/NACK when a downlink grantchannel is positioned in a single CC and an uplink ACK/NACK transmissionalso occurs in the single CC will be described. In this case, a methodof selecting a channel level resource within the same carrier andthereby transmitting the selected resource may be employed.

Method 2—method of selecting a channel level resource within the samecarrier and thereby transmitting the selected resource:

In a case where a data transmission is performed through two downlinkCCs and a grant channel is transmitted to a single downlink CC, a singleuplink CC for transmitting ACK/NACK may be predetermined.

When the single uplink CC for transmitting ACK/NACK is referred to asUL-CC0 and two ACK/NACK channels assigned within UL-CC0 are classifiedas CH0 and CH1, a signal transmission channel may be selected from CH0and CH1 as shown in Table 14. When a BPSH modulation is performed,ACK/NACK corresponding to 2 bits may be transmitted. The base stationmay identify ACK/NACK through detection of a transmission symbol anddetection of a channel corresponding to a signal transmission in UL-CC0.

TABLE 14 transmission symbol and channel for transmitting ACK/NACKACK/NACK signal trans- transmission bit value mission channel symbol 00CH0 0 01 CH0 1 10 CH1 0 11 CH1 1

Hereinafter, a method of transmitting ACK/NACK and a scheduling requestusing a channel selection method will be described.

1) Method of transmitting ACK/NACK using scheduling request resource:

The terminal may simultaneously transmit ACK/NACK and a schedulingrequest in a single subframe. In this case, the terminal may be assignedin advance with a resource for the scheduling request, and may transmita scheduling request signal using the assigned scheduling requestresource only when the terminal needs to send scheduling request to thebase station.

If the terminal determines that ACK/NACK transmission in response todownlink data transmission only in the downlink PCC and the schedulingrequest occur in the same subframe, the terminal may transmit ACK/NACKusing the scheduling request resource instead of using an ACK/NACKresource, which is similar to Rel-8/9.

It may be assumed that ACK/NACK transmission uses one of theaforementioned channel selection schemes. Specifically, a number ofchannels assigned according to a number of bits of ACK/NACK to betransmitted may be assumed as shown in Table 15.

TABLE 15 number of channels assigned according to a number of ACK/NACKbits Number Maximum number of of A/N A/N channels required bits forchannel selection 2 2 3 3 4 4

Channel selection mapping relationship according to the number ofACK/NACK bits may need to be predefined. For example, when the number ofA/N bits is Q, a Q-bit channel selection mapping table correspondingthereto may be defined.

When the terminal needs to transmit ACK/NACK in a subframe wherescheduling request transmission does not occur, the channel selectionmay be performed based on the channel selection mapping relationshippredefined according to the number of bits of ACK/NACK to betransmitted.

The number of ACK/NACK bits to be transmitted by the terminal may bedetermined based on the number of configured CCs for the terminal andthe transmission mode of configured CCs. For example, 2 bits may be usedfor a CC configured with a transmission mode capable of transmittingmaximum two transport blocks, and 1 bit may be used for a CC configuredwith a transmission mode capable of transmitting a maximum singletransport block. When N denotes a total number of ACK/NACK bits,

$N = {\sum\limits_{i = 1}^{\;_{C_{N}}}{Q_{i}.}}$Here, Q_(i) denotes the number of ACK/NACK bits with respect to ani^(th) configured CC, and C_(N) denotes the number of configured CCs forthe terminal.

A case where the terminal needs to transmit ACK/NACK in a subframe wherescheduling request transmission may occur will be described. In thiscase, a resource for the scheduling request transmission is secured inthe subframe and thus, the total number of available resources mayincrease by one compared to a case where only ACK/NACK transmissionoccurs. Accordingly, channel selection may be performed based on channelselection mapping relationship that is obtained by further adding asingle bit to the number of ACK/NACK bits. Specifically, the channelselection mapping table used by the terminal in the subframe where thescheduling request transmission may occur may be expressed as shown inTable 16.

TABLE 16 channel selection mapping table used by the terminal in thesub- frame where the scheduling request transmission may occur Number ofchannel selection A/N bits mapping table 2 3-bit table 3 4-bit table 45-bit table

When the occurrence of the scheduling request is considered as ACK andthe non-occurrence of the scheduling request is considered as NACK ordiscontinuous transmission (DTX), the channel selection mapping tablegenerated for ACK/NACK may be employed even in a subframe where thescheduling request and ACK/NACK simultaneously occur.

For example, the 3-bit A/N table may be assumed as Table 17.

TABLE 17 3-bit A/N Table transmission transmission b0 b1 b2 channelsymbol D N/D N/D no transmission null N N/D N/D Ch0  1 A N/D N/D Ch0 −1N/D A N/D Ch1 −j A A N/D Ch1  j N/D N/D A Ch2  1 A N/D A Ch2  J N/D A ACh2 −j A A A Ch2 −1

Referring to Table 17, N/D may be mapped to negative SR corresponding tothe non-occurrence of the scheduling request and A may be mapped topositive SR corresponding to the occurrence of the scheduling request byconsidering b2 as scheduling request information. Using the abovemethod, a table for 2-bit A/N and the scheduling request may begenerated from the 3-bit A/N mapping table. The table may be expressedby Table 18.

TABLE 18 table for 2-bit A/N and SR transmission transmission b0 b1 SRchannel symbol D N/D Negative no transmission null N N/D Negative Ch0  1A N/D Negative Ch0 −1 N/D A Negative Ch1 −j A A Negative Ch1  J N/D N/DPositive Ch2  1 A N/D Positive Ch2  J N/D A Positive Ch2 −j A A PositiveCh2 −1

For example, the 4-bit A/N table may be assumed as Table 19.

TABLE 19 4-bit A/N table transmission transmission b0 b1 b2 b3 channelsymbol D N/D N/D N/D no transmission null N N/D N/D N/D Ch0 1 A N/D N/DN/D Ch0 −1 N/D A N/D N/D Ch1 −j A A N/D N/D Ch1 J N/D N/D A N/D Ch2 1 AN/D A N/D Ch2 J N/D A A N/D Ch2 −j A A A N/D Ch2 −1 N N/D N/D A Ch3 1 AN/D N/D A Ch0 −j N/D A N/D A Ch3 J A A N/D A Ch0 J N/D N/D A A Ch3 −j AN/D A A Ch3 −1 N/D A A A Ch1 1 A A A A Ch1 −1

Referring to Table 19, N/D may be mapped to negative SR corresponding tothe non-occurrence of the scheduling request and A may be mapped topositive SR corresponding to the occurrence of the scheduling request byconsidering b3 as scheduling request information. Using the abovemethod, a table for 3-bit A/N and the scheduling request may begenerated from the 4-bit A/N mapping table. The table may be expressedby Table 20.

TABLE 20 table for 3-bit A/N and SR transmission transmission b0 b1 b2SR channel symbol D N/D N/D Negative no transmission null N N/D N/DNegative Ch0 1 A N/D N/D Negative Ch0 −1 N/D A N/D Negative Ch1 −j A AN/D Negative Ch1 J N/D N/D A Negative Ch2 1 A N/D A Negative Ch2 J N/D AA Negative Ch2 −j A A A Negative Ch2 −1 N N/D N/D Positive Ch3 1 A N/DN/D Positive Ch0 −j N/D A N/D Positive Ch3 J A A N/D Positive Ch0 J N/DN/D A Positive Ch3 −j A N/D A Positive Ch3 −1 N/D A A Positive Ch1 1 A AA Positive Ch1 −1

As another example, the 3-bit A/N table may be assumed as Table 21.

TABLE 21 3-bit A/N mapping table transmission channel & transmissionsymbol CC0 CC1 CH1 CH2 CH3 A,A A −1 A,N A j N,A A −j N,N A −1 A,A N −1A,N N j N,A N −j N,N N 1 A,A D −1 A,N D j N,A D −j N,N D 1 D,D A −1 D,DN 1 D,D D no transmission

Referring to Table 21, N/D may be mapped to negative SR corresponding tothe non-occurrence of the scheduling request and A may be mapped topositive SR corresponding to the occurrence of the scheduling request byconsidering a second bit of CC0 as scheduling request information. Usingthe above method, a table for 2-bit A/N and the scheduling request maybe generated from the 3-bit A/N mapping table. The table may beexpressed by Table 22.

TABLE 22 mapping table for 2-bit A/N and SR transmission channel &transmission symbol CC0 CC1 CH1 CH2 CH3 A, Positive A −1 A, Negative A jN, Positive A −j N, Negative A −1 A, Positive N −1 A, Negative N j N,Positive N −j N, Negative N 1 A, Positive D −1 A, Negative D j N,Positive D −j N, Negative D 1 D, Negative A −1 D, Negative N 1 D,Positive A −j D, Positive N 1 D, Positive, D 1 D, Negative D notransmission

As another example, the 4-bit A/N table may be assumed as Table 23.

TABLE 23 4-bit A/N table transmission channel & transmission symbol CC0CC1 CH1 CH2 CH3 CH4 A,A A,A −1 A,N A,A −j N,A A,A −j N,N A,A −1 A,A A,Nj A,N A,N 1 N,A A,N 1 N,N A,N j A,A N,A −1 A,N N,A j N,A N,A −j N,N N,A1 A,A N,N −1 A,N N,N j N,A N,N −j N,N N,N 1 A,A D,D −1 A,N D,D j N,A D,D−j N,N D,D 1 D,D A,A −1 D,D A,N j D,D N,A 1 D,D N,N No transmission D,DD,D No transmission

Referring to Table 23, N/D may be mapped to negative SR corresponding tothe non-occurrence of the scheduling request and A may be mapped topositive SR corresponding to the occurrence of the scheduling request byconsidering a second bit of CC1 as scheduling request information. Usingthe above method, a table for 3-bit A/N and the scheduling request maybe generated from the 3-bit A/N mapping table. The table may beexpressed by Table 24.

TABLE 24 table for 3-bit A/N and SR transmission channel & CC0 CC1transmission symbol (CC1) (CC0) CH1 CH2 CH3 CH4 A,A A, Positive −1 A,NA, Positive −j N,A A, Positive −j N,N A, Positive −1 A,A A, Negative jA,N A, Negative 1 N,A A, Negative 1 N,N A, Negative j A,A N, Positive −1A,N N, Positive j N,A N, Positive −j N,N N, Positive 1 A,A N, Negative−1 A,N N, Negative j N,A N, Negative −j N,N N, Negative 1 A,A D,Negative −1 A,N D, Negative j N,A D, Negative −j N,N D, Negative 1 A,AD, Positive −1 A,N D, Positive j N,A D, Positive −j N,N D, Positive 1D,D A, Positive −1 D,D A, Negative j D,D N, Positive 1 D,D N, NegativeNo transmission D,D D, Negative No transmission D,D D, Positive 1

The base station may need to monitor whether a terminal makes ascheduling request in a subframe where a scheduling request resource ofthe terminal is assigned. When the terminal does not transmit ACK/NACKin the subframe where the scheduling request resource is assigned, thebase station may determine whether the scheduling request is received bydetecting a signal in the corresponding scheduling request resource.

In the case of 4-bit ACK/NACK and scheduling request:

1. A channel selection mapping table is generated and is transmittedaccording to a channel selection scheme.

2. Reed-Muller (RM) coding is performed with respect to 5-bitinformation including 4-bit ACK/NACK and a 1-bit scheduling request andthen the RM coded information is transmitted according to a DFT-S-OFDMA/N transmission scheme, which is disclosed in subclauses 1.2.2.4.3 and1.4.2.1.

3. Bundling is performed with respect to ACK/NACK and then acorresponding result is transmitted to the scheduling request resource,which is disclosed in subclause 1.5.1.

2) Method of Transmitting Reduced ACK/NANCK Information Using aScheduling Request Resource in Order to Indicate Positive SR:

This method relates to a method of transmitting reduced ACK/NACKinformation using the scheduling request resource in order to indicatepositive SR when positive SR and A/N transmission simultaneously occur.In the case of negative SR, even a subframe where the scheduling requestresource is assigned may transmit only ACK/NACK information according toa channel selection scheme. Basically, in the case of positive SR, anumber of PDSCHs successfully received may be counted and then betransmitted using the scheduling request resource by indicating thecounted number of PDSCHs in a single QPSK transmission symbol. As shownin Table 25, two bit values b(0) and b(1) may be indicated based on thenumber of PDSCHs that the terminal determines are successfully received,and then may be transmitted. Here, that a PDSCH is successfully receivedindicates that all the transport blocks included in the PDSCH havepassed a cyclic redundancy check (CRC). When even a single transportport block fails in the CRC test, the PDSCH may not be determined to besuccessfully received.

In this instance, a Rel-8/9 fallback scheme may not be employed forsimultaneous transmission of the scheduling request and ACK/NACK. TheRel-8/9 fallback scheme corresponds to a method of transmitting ACK/NACKinformation using the scheduling request resource in order to indicatepositive SR when a downlink resource assignment is present in a downlinkPCC. This is because the base station may not discriminate a case wherethe Rel-8/9 fallback scheme is employed since a PDSCH is unsuccessfullyreceived from the aforementioned case where the counted number ofsuccessfully received PDSCHs is transmitted. The Rel-8/9 fallback schememay be employed for DFT-S-OFDM based ACK/NACK without this problem.

TABLE 25 Number of successfully b(0), received PDSCHs b(1) 0 0, 0 1 1, 12 1, 0 3 0, 1 4 1, 1

Hereinafter, ACK/NACK information reduced in another form will bedescribed. Here, it may be assumed that maximum two CCs receive a PDSCH.In the case of negative SR, even the subframe where the schedulingrequest resource is assigned may transmit only ACK/NACK informationaccording to the channel selection scheme. In the case of positive SR,ACK/NACK bundling may be performed with respect to a codewordtransmitted from each CC. In this instance, DTX and NACK may not bediscriminated from each other. Specifically, when two codewords aretransmitted from a single CC, a case where all of the two codewords arcACK may be indicated as ACK. A case where either of the two codewords isNACK may be indicated as NACK/DTX. b(0) and b(1) may be determined byapplying Table 26 to a bundled ACK/NACK state with respect to each ofthe two CCs.

TABLE 26 bundled ACK/NACK state Bundled ACK/NACK state b(0), of each ofCC0 and CC1 b(1) NACK/DTX, NACK/DTX 0, 0 ACK, ACK 1, 1 ACK, NACK/DTX 1,0 NACK/DTX, ACK 0, 1

According to an aspect, a single ACK/NACK channel may be assignedaccording to assignment of a two-dimensional (2D) sequence. The 2Dsequence may include a frequency-domain sequence and a time-domainsequence. The time-domain sequence may include a sequence for thereference signal part and a sequence for the ACK/NACK data part. When Nchannels are assigned as ACK/NACK resources, N 2D sequences may beassigned. That is, N 2D sequences may be assigned for each slot.

It may be assumed that N 2D sequences belong to the same resource block.

A user equipment (UE) may transmit ACK/NACK according to the followingsequence selection.

(1) The UE may select a single 2D sequence from the N 2D sequences.

In this case, the total number of cases that the UE may select is N.

(2) The UE may select a single 2D sequence from the N 2D sequencesindependently for each slot.

In this case, the total number of cases that the UE may select is N×N.

(3) Independently for each slot, the UE may select a single referencesignal sequence from N reference signal sequences and may select asingle data sequence from N ACK/NACK data sequences.

In this case, the total number of cases that the UE may select isN×N×N×N.

(4) For both slots, the UE may select a single reference signal sequencefrom N reference signal sequences and may select a single data sequencefrom N ACK/NACK data sequences.

In this case, the total number of cases that the UE may select is N×N.

In the case of (2), the sequence selection may be performed on aper-slot basis. Specifically, a single sequence may be selected from Nsequences in the first slot, and a single sequence may be selected fromN sequences in the second slot. According to the above selection, theremay be a total of N×N different cases. For example, when N=2, 2×2=4cases of selection may exist. Accordingly, information corresponding to2 bits may be transmitted through the sequence selection.

In the case of (3), the sequence selection may be further divided into asequence selection of the reference signal part and a sequence sectionof the ACK/NACK data part. Specifically, a single sequence may beselected from N reference signal sequences and a single sequence may beselected from N sequences in the ACK/NACK data part. According to theabove scheme, N×N cases may exist for each slot. When two slots areallowed for independent selection, a total of N×N×N×N cases may bepossible. For example, when N=2, a total of 2×2×2×2=16 cases may exist.Accordingly, information corresponding to 4 bits may be transmittedthrough the above sequence selection.

In the case of (4), the sequence selection may be further divided into asequence selection of the reference signal part and a sequence selectionof the ACK/NACK data part. But the sequence selection takes place on aper-subframe (two slots) basis. Specifically, a single sequence may beselected from N reference signal sequences and a single sequence may beselected from N sequences in the ACK/NACK data part. According to theabove scheme, N×N cases may exist for each slot. When two slots areallowed for independent selection, a total of N×N cases may be possible.For example, when N=2, a total of 2×2=4 cases may exist. Accordingly,information corresponding to 2 bits may be transmitted through the abovesequence selection.

In an LTE system and an LTE-Advanced system, a single downlink grant maytransmit two transport blocks. Accordingly, ACK/NACK corresponding to asingle grant may include 2 bits. Also, DTX corresponds to a case wherean eNode-B (eNB) transmits a grant, however, a UE does not receive thegrant. For example, the UE may have five states with respect to thesingle grant. When the eNB transmits all of N grants to the UE, the UEmay have maximum 5^(N) ACK/NACK states. The UE may need to notify theeNB of its ACK/NACK states.

Hereinafter, a method of transmitting ACK/NACK states using theaforementioned sequence selection scheme will be described.

When N=5, the terminal may be able to distinguish maximum 5⁵=3125ACK/NACK states. When using the sequence selection scheme, a total of 5⁴cases may exist. When information is transmitted by applying a QPSKmodulation to a selected sequence, a total of 5⁴×4=2500 cases may bedistinguished by combining the sequence selection scheme and amodulation symbol. Specifically, since the number of states that can beexpressed is smaller than 5⁵ states, all of the 5⁵ states, cannot bedistinguished. In this case, when two transport blocks are transmittedwith respect to a predetermined grant among five grants, it is possibleto employ a scheme of not discriminating state (NACK, NACK) from state(DTX, DTX) for the pre-determined grant. In this case, the maximumnumber of states that can be distinguished by the terminal may be given5⁴×4 and thus, it is possible to indicate a total of 5⁴×4=2500 cases bycombining the sequence selection and the modulation symbol.

When N=4, the terminal may be able to distinguish maximum 5⁴=625ACK/NACK states. When using the sequence selection scheme, a total of 4⁴cases may exist. When information is transmitted by applying a QPSKmodulation to a selected sequence, a total of 4⁴×4=1024 cases may beindicated by combining a sequence selection and a modulation symbol.Specifically, since that number of states to be expressed is greaterthan 625, it is possible to transmit ACK/NACK states to the eNB throughthe sequence selection and the QPSK modulation.

Similarly, when N=3, the terminal may indicate maximum 5³=125 ACK/NACKstates. When using the sequence selection scheme, a total of 3⁴ casesmay exist. When information is transmitted by applying a QPSK modulationto a selected sequence, a total of 3⁴×4=324 cases may be indicated bycombining a sequence selection and a modulation symbol. Specifically,since the number of states to be expressed is greater than 125, ACK/NACKstates may be transmitted to the eNB through the sequence selection andthe QPSK modulation. In this case, even though a BPSK modulation isemployed, a total of 162 cases may be indicated and thus, 125 ACK/NACKstates may be indicated.

Similarly, when N=2, the terminal may indicate maximum 5²=25 ACK/NACKstates. When using the sequence selection scheme, a total of 24 casesmay exist. When information is transmitted by applying a BPSK modulationor a QPSK modulation to a selected sequence, a total of 2⁴×2=32 or2⁵×2=64 cases may be indicated by combining a sequence selection and amodulation symbol.

Specifically, since the number of states to be expressed is greater than25, ACK/NACK states may be transmitted to the eNB through the sequenceselection and the BPSK modulation or the QPSK modulation.

When N=1, the terminal may indicate maximum five ACK/NACK states. Inthis case, using a QPSK modulation, four cases may be indicated andinformation may be indicated as that a DTX of the terminal does nottransmit any signal. Accordingly, maximum five states may be indicated.

The terminal may need to simultaneously transmit ACK/NACK and ascheduling request in a single subframe. The terminal may be assigned inadvance with a resource for the scheduling request and may transmit ascheduling request signal using the assigned rescheduling requestresource only when the terminal needs to request the base station forthe scheduling request. It may be assumed that one of the aforementionedchannel or sequence selection schemes is used for ACK/NACK transmission.The base station may need to monitor whether a corresponding terminalmakes a scheduling request in a subframe where a scheduling requestresource of a predetermined terminal is assigned. When the terminal doesnot transmit ACK/NACK in the subframe where the scheduling requestresource is assigned, the base station may detect a signal in thecorresponding scheduling request resource and determine whether thescheduling request is present. When the terminal transmits ACK/NACK inthe subframe where the scheduling request resource is assigned, a signaltransmitted by the terminal may need to include ACK/NACK and whether ofthe scheduling request. For this, in the subframe where the schedulingrequest resource is assigned, a channel or sequence selection may beperformed using both an ACK/NACK resource and the scheduling requestresource.

In a subframe where the scheduling request resource is not assigned tothe terminal, the terminal may perform the channel or sequence selectionusing PUCCH ACK/NACK channel(s) assigned for ACK/NACK transmission. Inthe subframe where the scheduling request resource is assigned to theterminal, the terminal may perform the channel or sequence selectionusing the PUCCH ACK/NACK channel(s) assigned for ACK/NACK transmissionand a PUCCH scheduling request resource.

In this instance, when employing a sequence selection scheme ofindependently selecting a sequence with respect to each of a dataportion and a reference signal portion, both a PUCCH ACK/NACK resourceand a PUCCH scheduling request resource may need to be present withinthe same resource block resource. When a reference signal sequence and adata sequence are transmitted in the same resource block, information ofa symbol carried in data may be demodulated by performing channelestimation with respect to a data block. For example, when the terminalis assigned with two PUCCH ACK/NACK resources in the subframe where thescheduling request resource is not assigned, the terminal may select asingle sequence from two reference signal sequences and also select asingle sequence from two data sequences. When a symbol transmitted to adata block is a QPSK, a total of 2×2×4=16 cases may be indicated, whichmay correspond to 4-bit information. When the terminal is assigned withtwo PUCCH ACK/NACK resources in a predetermined subframe for ACK/NACKtransmission and a PUCCH scheduling request resource is present in thesubframe, three resources may need to be present in the same resourceblock. The terminal may use all of three resources and thus, may selecta single reference signal sequence from three reference signal sequencesand then select a single sequence from three data sequences. When asymbol transmitted to a data block is a QPSK, a total of 3×3×4=36 casesmay be indicated using the above method, which may correspond to 5-bitinformation. Since ACK/NACK uses only four bits, a remaining single bitmay indicate whether there is the scheduling request or not.

FIG. 4 is a diagram illustrating a channel structure according to anembodiment of the present invention.

FIG. 4 illustrates a channel structure when a normal CP is used.Referring to FIG. 4 , a plurality of terminals may be code divisionmultiplexed to the same physical resource using a 2D spreading scheme.In this case, spreading may be performed by applying a length-12sequence in the frequency domain and by applying a length-3 DFT sequencein the time domain. When using the normal CP, ACK/NACK may be spreadusing a length-4 Walsh sequence.

In the channel structure of FIG. 4 , a transmission method of FIG. 5 maybe employed to apply a relatively large number of ACK/NACK symbols whilemaintaining positions of reference signals and ACK/NACK data.

FIG. 5 is a block diagram illustrating a configuration of a terminalaccording to an embodiment of the present invention.

Referring to FIG. 5 , the terminal may include a modulation unit 510, aDFT unit 520, an inverse fast Fourier transform (IFFT) unit 530, and aCP inserter 540, and a radio frequency (RF) unit 550.

The modulation unit 510 may modulate a channel coded bitstream, and theDFT unit 520 may perform DFT on the modulated symbols. The modulatedsymbols may be mapped to N subcarriers. The N symbols mapped to Nsubcarriers may be referred to as a symbol block. The IFFT unit 530 mayperform IFFT on the symbol block. The CP inserter 540 and the RF unit550 may transmit inverse fast Fourier transformed symbol blocks.

When a PUSCH uses a normal CP, seven symbol blocks may be transmittedfor each slot. Among the seven symbol blocks, the fourth symbol blockmay be used as a reference signal. When an extended CP is used, sixsymbol blocks may be transmitted for each slot. Among the six symbolblocks, the third symbol block may be used as a reference signal. Asymbol block corresponding to the reference signal may directly map eachsymbol predefined in each subcarrier in the frequency domain.

In a structure where a single reference signal is transmitted for eachslot, when the terminal moves at a relatively high speed, a receptionquality may decrease due to deterioration in a channel estimationperformance. In the case of a data transmission, a reception successrate may be increased through a Hybrid Automatic Request (HARQ)retransmission by enabling the terminal to retransmit a data block forwhich a reception error has occurred. However, since retransmission ofcontrol information such as ACK/NACK is not allowed, the receptionsuccess rate may need to be high for a one-time transmission.

As shown in FIG. 4 , to obtain frequency diversity, an ACK/NACK channelmay perform slot-level frequency hopping, where a transmission frequencydomain may vary on a per-slot basis. Also, the terminal may include asingle transmit antenna or a plurality of transmit antennas. When theterminal uses the plurality of transmit antennas, it is assumed thatonly a single layer is transmitted through precoding.

A first method is to use two reference signals per a single slot asshown in FIG. 6 . When two reference signals are used for each slot asshown in FIG. 6 , the base station may maintain a channel estimationperformance even for a terminal with high speed.

A second method is to multiplex ACK/NACK information from a plurality ofterminals into the same radio resource. A reference signal may be spreadalong the frequency axis using a sequence, and ACK/NACK may be spreadalong the time axis. To identify information transmitted from differentterminals, the reference signals may be assigned with orthogonalfrequency-domain sequences and the ACK/NACK data blocks may be assignedwith orthogonal time-domain sequences.

A DFT sequence may be used as the orthogonal time-domain sequence tospread the ACK/NACK data block. When a normal CP is used as shown in apart (A) FIG. 6 , a length-5 DFT sequence may be used as shown in Table27.

TABLE 27 length-5 DFT sequence Sequence index DFT sequence 0 [1 1 1 1 1]1 [1 e^(j2π/5) e^(j4π/5) e^(j6π/5) e^(j8π/5)] 2 [1 e^(j4π/5) e^(j8π/5)e^(j12π/5) e^(j16π/5)] 3 [1 e^(j6π/5) e^(j12π/5) e^(j18π/5) e^(j24π/5)]4 [1 e^(j8π/5) e^(j16π/5) e^(j24π/5) e^(j32π/5)]

When an extended CP is used as shown in a part (B) of FIG. 6 , alength-4 DFT sequence as shown in Table 28 or a length-4 Walsh sequenceas shown in Table 29 may be used.

TABLE 28 length-4 DFT sequence Length-4 DFT sequence Sequence index DFTsequence 0 [1 1 1 1] 1 [1 e^(j2π/4) e^(j4π/4) e^(j6π/4)] 2 [1 e^(j4π/4)e^(j8π/4) e^(j12π/4)] 3 [1 e^(j6π/4) e^(j12π/4) e^(j18π/4)]

TABLE 29 length-4 Walsh sequence Length-4 Walsh sequence Sequence indexWalsh sequence 0 [1 1 1 1] 1 [1 −1 1 −1] 2 [1 1 −1 −1] 3 [1 −1 −1 1]

Depending on channel environments of a cell, only a subset of atime-domain sequence may be used. For example, in an environment whereterminals rapidly move in the cell, only a sequence with a sequenceindex (0, 2) or only a sequence with a sequence index (1, 3) in Table 27may be used.

In the case of the length-4 DFT sequence, only a sequence with asequence index (0, 2) or only a sequence with a sequence index (1, 3) inTable 28 may be used.

In the case of the length-4 Walsh sequence, a sequence with a sequenceindex (0, 1), (1, 2), (2, 3), or (3, 1) in Table 29 may be used. Thismay be desirable to maintain the orthogonality in a high speedenvironment.

According to an aspect, as shown in a part (A) of FIG. 7 , a singlesymbol block positioned in the center may be used as a reference signaland a sequence with a spreading factor 3 or 6 may be used as atime-domain sequence of the data part.

In the case of the reference signal, it is possible to identifydifferent terminals by assigning orthogonal frequency-domain sequences.The same length of 12 as in an existing PUCCH or a length greater than12 may be employed as the length of a sequence applied along thefrequency axis. Accordingly, when the length of the time-domain sequenceis 3 or 6, it is possible to multiplex maximum three or six differentterminals into the same resource using the above method.

When the extended CP is used, a sequence with a spreading factor 2 and asequence with a spreading factor 3 may be used together as a time-domainsequence of the data area or a sequence with a spreading factor 5 may beused as the time-domain sequence of the data area. Referring to a part(B) of FIG. 7 , the sequence with the spreading factor 5 may be appliedto symbol blocks BL #0, BL #1, BL #3, BL #4, and BL #5. In a structurewhere the extended CP is used and a single reference signal is used, itmay be desirable to locate the reference signal in the symbol block BL#2. When a shortened format is used, the last block of a second slot maynot be transmitted. Compared to a case where the reference signal ispresent in the symbol block BL #3, when the reference signal is presentin the symbol block BL #2, the reference signal may be positioned in themiddle of ACK/NACK data blocks whereby an accuracy of channel estimationmay further increase.

According to an aspect, when a normal CP is used, three symbol blocksmay be used as a reference signal as shown in a part (A) of FIG. 8 and asequence with a spreading factor 2 or 4 may be used as a time-domainsequence of a data area. When the sequence with the spreading factor 2is used, a length-2 sequence may be applied to symbol blocks BL #1 andBL #2, and BL #4, and BL #5 shown in the part (A) of FIG. 8 . When asequence with a spreading factor 4 is used, a length-4 sequence may beapplied to the symbol blocks BL #1, BL #2, BL #4, and BL #5 shown in thepart (A) of FIG. 8 . In the case of the reference signal, it is possibleto identify different terminals by assigning an orthogonalfrequency-domain sequence. The same length of 12 as in an existing PUCCHor a length of greater than 12 may be used as a length of a sequenceused for a frequency-domain. When the length of the time-domain sequenceis 2 or 4, it is possible to multiplex maximum two or four differentterminals into the same resource.

When the extended CP is used, a length-2 sequence may be applied tosymbol blocks BL #0 and BL #1, and BL #4 and BL #5 as shown in a part(B) of FIG. 8 . When a sequence with a length 4 is used, a length-4sequence may be applied to the symbol blocks BL #0, BL #1, BL #4, and BL#5. Accordingly, when the length of the time-domain sequence is 2 or 4,it is possible to multiplex maximum two or four different terminals intothe same resource.

Table 30, Table 31, and Table 32 show examples of a length-2 Walshsequence, a length-3 DFT sequence, and a length-6 DFT sequence.

TABLE 30 sequence index Walsh sequence 0 [1 1] 1 [1 −1]

TABLE 31 sequence index DFT sequence 0 [1 1 1] 1 [1 e^(j2π/3) e^(j4π/3)]2 [1 e^(j4π/3) e^(j2π/3)]

TABLE 32 Sequence index DFT sequence 0 [1 1 1 1 1 1] 1 [1 e^(j2π/6)e^(j4π/6) e^(j6π/6) e^(j8π/6) e^(j10π/6)] 2 [1 e^(j4π/6) e^(j8π/6)e^(j12π/6) e^(j16π/6) e^(j20π/6)] 3 [1 e^(j6π/6) e^(j12π/6) e^(j18π/6)e^(j24π/6) e^(j30π/6)] 4 [1 e^(j8π/6) e^(j16π/6) e^(j24π/6) e^(j32π/6)e^(j40π/6)] 5 [1 e^(j10π/6) e^(j20π/6) e^(j30π/6) e^(j40π/6) e^(j50π/6)]

According to an aspect, when a normal CP is used, three symbol blocks BL#2, BL #3, and BL #4 may be used as a reference signal and a sequencewith a spreading factor 2 or 4 may be used as a time-domain sequence ofthe data area.

For example, when the sequence with the spreading factor 2 is used, alength-2 sequence may be applied to symbol blocks BL #0 and BL #1, andBL #5 and BL #6. When the sequence with the spreading factor 4 is used,a length-4 sequence may be applied to the symbol blocks BL #0, BL #1, BL#5, and BL #6.

In the case of the reference signal, it is possible to identifydifferent terminals by assigning orthogonal frequency-domain sequences.The same length of 12 as in an existing PUCCH or a length greater than12 may be employed as the length of a sequence applied along thefrequency axis. Accordingly, when the length of the time-domain sequenceis 2 or 4, it is possible to multiplex maximum two or four differentterminals into the same resource.

In a subframe where a sounding reference signal is transmitted, the lastblock of a second slot of an ACK/NACK channel may not be transmitted. Inthe structure shown in the part (A) of FIG. 6 , the symbol block BL #6corresponding to the last block of the second slot may not betransmitted. Since the number of ACK/NACK data blocks reduces from fiveto four, the number of terminals capable of performing transmissionusing the same radio resource block while maintaining orthogonaltransmission may also reduce from five to four. In the case of thereference signal block, no change may be made in the sequence while inthe case of an ACK/NACK data block, a change may be made only in thesecond slot. Specifically, orthogonal time-domain sequences beingapplied to the ACK/NACK data block of the second slot may use thelength-4 DFT sequences of Table 33 or the length-4 Walsh sequences ofTable 34.

TABLE 33 Sequence index DFT sequence 0 [1 1 1 1] 1 [1 e^(j2π/4)e^(j4π/4) e^(j6π/4)] 2 [1 e^(j4π/4) e^(j8π/4) e^(j12π/4)] 3 [1 e^(j6π/4)e^(j12π/4) e^(j18π/4)]

TABLE 34 Sequence index Walsh sequence 0 [1 1 1 1] 1 [1 −1 1 −1] 2 [1 1−1 −1] 3 [1 −1 −1 1]

Hereinafter, a method of randomizing intra-cell interference andinter-cell interference when using the aforementioned DFT-S-OFDM basedACK/NACK transmission method will be described.

It may be assumed that cyclic shifted versions of a Constant AmplitudeZero Auto-Correlation (CAZAC) sequence are used as frequency-domainsequences as in the PUCCH of the LTE Release 8.

1) Intra-Cell Interference Randomization:

It is possible to randomize interference between terminals transmittingACK/NACK using the same resource in a cell by applying a differentcyclic shift and a different time-domain sequence used for referencesignal blocks and ACK/NACK data blocks in the two slots. According to anaspect, a cyclic shift used for reference signal blocks may bedifferently set in the first slot and the second slot. Specifically, thecyclic shift may be remapped in the second slot. A time-domain sequenceused for ACK/NACK data blocks may be differently set in the first slotand the second slot. Specifically, the time-domain sequence may beremapped in the second slot.

Specifically, in the structure shown in the part (A) of FIG. 6 ,interference of the time-domain sequence may be randomized with respectto ACK/NACK data blocks as follows.

As described above, in the structure shown in the part (A) FIG. 6 , thetime-domain sequence with the length of 5 used for the symbol blocks BL#0, BL #2, BL #3, BL #4, and BL #6 may use a DFT sequence of Table 35.

TABLE 35 Sequence index DFT sequence 0 [1 1 1 1 1] 1 [1 e^(j2π/5)e^(j4π/5) e^(j6π/5) e^(j8π/5)] 2 [1 e^(j4π/5) e^(j8π/5) e^(j12π/5)e^(j16π/5)] 3 [1 e^(j6π/5) e^(j12π/5) e^(j18π/5) e^(j24π/5)] 4 [1e^(j8π/5) e^(j16π/5) e^(j24π/5) e^(j32π/5)]

In Table 35, a single DFT sequence may be indicated as O_(i)=[D_(i)(0),D_(i)(1), D_(i)(2), D_(i)(3), D_(i)(4)] where 1 denotes the sequenceindex. Slot-level remapping enables a DFT sequence used in the firstslot and a DFT sequence used in the second slot to be different fromeach other. Accordingly, when Q_(i) is used in the first slot, Q_(j) maybe used in the second slot. Here, j≠i or j=i.

To normalize interference experienced by terminals, remapping may beperformed by considering the following elements. Initially, when usingthe DFT sequence disclosed in Table 35, an aspect that the orthogonalitymay be further maintained as sequence indices are further separate fromeach other may be considered. For example, referring to Table 35, anamount of the average interference between O₀ and O₂ may be less than anamount of the average interference between O₀ and O₁. Accordingly, whentwo terminals use neighboring sequences in the first slot, the twoterminals may use non-neighboring sequences in the second slot.

In contrast, when the two terminals use non-neighboring sequences in thefirst slot, the two terminals may use neighboring sequences in thesecond slot. The above method may be easily performed by determining aDFT sequence assignment order in the second slot so that an indexdifference may become 2, for example, {0, 2, 4, 1, 3}. Table 36 shows anexample of effective remapping of the time-domain sequence

TABLE 36 DFT (Example 1) (Example 2) sequence in DFT sequence DFTsequence Terminal first slot in second slot in second slot UE0 O₀ O₀ O₀UE1 O₁ O₂ O₃ UE2 O₂ O₄ O₁ UE3 O₃ O₁ O₄ UE4 O₄ O₃ O₂

For example, a terminal UE 1 may use 01 in the first slot and beremapped in the second slot to thereby use O₂ in example 1 of Table 36.The terminal UE1 may receive a largest amount of interference from UE0and UE2 using neighboring sequence indices in the first slot, and mayreceive a largest amount of interference from UE3 and UE4 usingneighboring sequence indices in the second slot. Most interferingterminals may be diversified over the first slot and the second slot andthereby an amount of interference between the terminals may benormalized. In Table 36, four sequence assignments {2, 4, 1, 3, 0}, {4,1, 3, 0, 2}, {1, 3, 0, 2, 4}, and {3, 0, 2, 3, 1} corresponding to acyclic rotation of {0, 2, 4, 1, 3} of Example 1 may have the sameeffect. Like {0, 3, 1, 4, 2} of example 2 of Table 36, sequence indicesmay be configured to cyclically decrease. Also in this case, foursequence assignments {3, 1, 4, 2, 0}, {1, 4, 2, 0, 3}, {4, 2, 0, 3, 1},and {2, 0, 3, 1, 4} corresponding to a cyclic rotation of {0, 3, 1, 4,2} may also have the same effect. Specifically, the same effect may beachieved only if a sequence index difference is configured to become 2.

When a shortened format is used in the second slot in the structureshown in the part (A) of FIG. 6 , the slot-level remapping may achievethe average normalization by appropriately selecting a length-5 DFTsequence used in the first slot and a length-4 sequence used in thesecond slot.

When a single DFT sequence of Table 35 is indicated as P_(i)=[D_(i)(0),D_(i)(1), D_(i)(2), D_(i)(3)] where i denotes a sequence index, and thisDFT sequence is used in the second slot, and when two terminals useneighboring sequences in the first slot, the terminals may be configuredto use non-neighboring sequences in the second slot if possible.Conversely, when the two terminals use non-neighboring sequences in thefirst slot, the two terminals may be configured to use neighboringsequences in the second slot. Through this, the interferencenormalization may be achieved. When four sequences O₀, O₁, O₂, and O₃among five sequences are used for the assignment in the first slot,P_(i) may be assigned in the second slot as shown in example 1 of Table37. Here, i denotes a sequence index of Table 35.

TABLE 37 DFT (Example 1) (Example 2) sequence in DFT sequence Walshsequence Terminal first slot in second slot in second slot UE0 O₀ P₀ W₀UE1 O₁ P₂ W₁ UE2 O₂ P₁ W₂ UE3 O₃ P₃ W₃

It may be assumed that a single Walsh sequence is indicated asW_(i)=[D_(i)(0), D_(i)(1), D_(i)(2), D_(i)(3)] where i denotes asequence index and this Walsh sequence is used in the second slot.Referring to the Walsh sequence of Table 34, an amount of interferencebetween sequences using neighboring indices may be less than an amountof interference between sequences using non-neighboring indices.Accordingly, when two terminals use neighboring DFT sequences in thefirst slot, the two terminals may be configured to use neighboring Walshsequences in the second slot. When the two terminals use non-neighboringDFT sequences in the first slot, the two terminals may be configured touse non-neighboring Walsh sequences in the second slot. Through this,the interference normalization may be achieved. When four sequences O₀,O₁, O₂, and O₃ among five sequences are used for the assignment in thefirst slot, W_(i) may be assigned in the second slot as shown in example2 of Table 37. Here, i denotes a sequence index of Table 32.

To further randomize interference in each terminal, a time-domainsequence to be assigned to each terminal may be differently assigned foreach subframe. According to the LTE Rel-8/9 standard, a single radioframe includes a total of ten consecutive subframes. Here, a singleradio frame lasts for 10 ms and a single subframe lasts for 1 ms. Forexample, when an assignment relationship of Table 37 is used for asingle subframe, time-domain sequences to be assigned to a terminal mayvary in another subframe as shown in Table 38.

TABLE 38 DFT (Example 1) (Example 2) sequence in DFT sequence DFTsequence Terminal first slot in second slot in second slot UE1 O₀ O₀ O₀UE4 O₁ O₂ O₃ UE0 O₂ O₄ O₁ UE2 O₃ O₁ O₄ UE3 O₄ O₃ O₂

In Table 36 and Table 38, a sequence assignment of a terminal may beexpressed by a leftmost terminal index column. For example, the sequenceassignment of the terminal may be indicated as {UE0, UE1, UE2, UE3, UE4}in Table 36, and may be indicated as {UE1, UE4, UE0, UE2, UE3} in Table38. A total of 5! (=120) different sequence assignments may exist.Accordingly, each of maximum 120 consecutive terminal sequenceassignments may be different in each subframe. When a sequenceassignment is desired to repeat based on a single frame unit, ten out of120 assignments may be selected and thereby be used. Ten sequences usedfor each cell may be selected to be different from each other.

2) Inter-Cell Interference Randomization:

Block-level cyclic shift hopping may be applied to a cyclic shift usedfor reference signal blocks. The block-level cyclic shift hopping mayindicate changing a cyclic shift based on a block unit. In the case ofan LTE Release 8, a reference signal used for a PUCCH may perform theabove cyclic shift hopping. A hopping pattern of the cyclic shift may begenerated by applying an offset to the cyclic shift. In this instance, ahopping pattern of the offset may be the same in each cell. For example,when terminals performing ACK/NACK transmission using the same resourcein a single cell have the same hopping pattern, the orthogonalitybetween the terminals may be maintained. In particularly, when thehopping pattern is set to be different between neighboring cells,hopping patterns of terminals between cells may be different from eachother and thus, interference may be randomized.

Block-level scrambling may be applied with respect to a time-domainsequence used for ACK/NACK data blocks. In this case, the samescrambling sequence may be used in a cell. For example, terminalsperforming ACK/NACK transmission using the same resource in a cell mayhave the same scrambling sequence so that the orthogonality between theterminals is maintained. Also, terminals belonging to different cellsmay have different scrambling sequences and thus, interference may berandomized.

As described above, in the structure shown in the part (A) of FIG. 6 ,the orthogonal time-domain sequence with the length of 5 used for thesymbol blocks BL #0, BL #2, BL #3, BL #4, and BL #6 may use the DFTsequence of Table 35. A single DFT sequence of Table 35 may be denotedas O_(i)=[D_(i)(0), D_(i)(1), D_(i)(2), D_(i)(3), D_(i)(4)]. Here, idenotes a sequence index. A scrambling sequence to be used together withthe DFT sequence O_(i) may be denoted as Q=[S(0), S(1), S(2), S(3),S(4)]. An element constituting the scrambling sequence may be providedin a form of S(i)=exp (jθ_(i)). By multiplying element-wise the DFTsequence O_(i) and the scrambling sequence Q element level, a sequenceR_(i) is obtained; R_(i)=[R_(i)(0), R_(i)(1), R_(i)(2), R_(i)(3),R_(i)(4)]=[D_(i)(0)S(0), D_(i)(1)S(1), D_(i)(2)S(2), D_(i)(3)S(3),D_(i)(4)S(4)]. After multiplying data symbols by the correspondingelements of R_(i), DFT may be performed. The above relationship may beexpressed as shown in FIG. 12 . Terminals transmitting ACK/NACK usingthe same radio resource block in a cell may use different DFT sequencesbut use the same scrambling sequence in order to maintain mutualorthogonality. Also terminals served by different cells may usedifferent scrambling sequences, which thus can achieve the inter-cellinterference randomization.

In the structure shown in the part (A) of FIG. 6 , when the shortenedformat is used in the second slot, the length-4 DFT sequence of Table 33or the length-4 Walsh sequence of Table 34 may be used as the orthogonaltime-domain sequence to be used for ACK/NACK data blocks in the secondslot. A single time-domain orthogonal sequence may be indicated asU_(i)=[D_(i)(0), D_(i)(1), D_(i)(2), D_(i)(3)]. Here, i denotes asequence index of Table 33 or Table 34. A scrambling sequence to be usedtogether with the orthogonal sequence U_(i) may be used as Q=[S(0),S(1), S(2), S(3)]. DFT may be performed by multiplying data symbols bycorresponding elements of sequence R_(i)=[R_(i)(0), R_(i)(1), R_(i)(2),R_(i)(3)]=[D_(i)(0)S(0), D_(i)(1)S(1), D_(i)(2)S(2), D_(i)(3)S(3)].Here, R_(i) may be obtained by multiplying element-wise the time-domainorthogonal sequence U_(i) and the scrambling sequence Q. Using theaforementioned method, the first slot may be processed as shown in FIG.12 and the second slot may be processed as shown in FIG. 13 .

Hereinafter, a form of the scrambling sequence Q=[S(0), S(1), S(2),S(3), S(4)] or Q=[S(0), S(1), S(2), S(3)] will be described. In general,taking S(i)=exp(j2πn_(i)/N) may be convenient for implementation.Specifically, phase modulation may be used to form phases with regularangular intervals on the complex plane. Here, N denotes an integer andn_(i) denotes an integer satisfying 0≤n_(i)<N. n_(i) may be obtained bygenerating a pseudo-random sequence and sequentially substitutingcorresponding values of the pseudo-random sequence. Accordingly, n_(i)may have a different value depending on the slot number and theDFT-S-OFDM symbol number. The repetition period, after which the samevalues repeat, may be configured to be at least one frame. When therepetition period is set to be a single frame, a generator of thepseudo-random sequence may be initialized at a start point in time ofeach frame. Here, terminals to be code division multiplexed using thesame resource in the same cell may need to use the same pseudo-randomsequence in order to maintain orthogonality. On the other hand, when thepseudo-random sequences are different for different cells, interferencebetween neighboring cells may be randomized. For this, by including cellidentity (ID) as a parameter for initialization of the pseudo-randomsequence, it is possible to generate and use a different pseudo-randomsequence for a different cell ID.

For reference, in FIGS. 12, 13, and 14 , sequences of a multiplicationof a sequence element [R_(i)(n) or D_(i)(n)] and a DFT operation may beswitched with each other. That is, in both a case where the DFToperation is performed in each figure and then the multiplication of thesequence element [R_(i)(n) or D_(i)(n)] is performed, and a case wherethe multiplication of the sequence element [R_(i)(n) or D_(i)(n)] isperformed and then the DFT operation is performed, the same results maybe obtained.

According to an aspect, prior to the DFT operation instead of S(i)S_(k)(i)=exp(j2πn_(i)k/N) (k=0, 1, 2, . . . 11) may be sequentiallymultiplied with respect to 12 complex symbols. When N=12, a portion ofmultiplying S_(k)(i) prior to the DFT operation may be replaced with acyclic shift in a frequency domain after the DFT operation. This isbecause the DFT operation has the following property.DFT[exp(j2πn _(i) k/12)F(k)](k)=DFT[F(k)](k−n _(i))

Specifically, when DFT with a magnitude of 12 is performed by employingexp(j2πn_(i)k/N) F(k) (k=0, 1, 2, . . . 11) as an input instead ofF=[F(0), F(1), . . . F(11)]with a length of 12, the corresponding resultmay become the same as the result obtained by performing n_(i) cyclicshift of the result obtained by performing the DFT operation withrespect to F. Accordingly, when employing the above property, theterminal may perform cyclic shift as many as n_(i) with respect to theresult obtained by performing the DFT operation with respect to eachACK/NACK data block as shown in FIG. 14 , instead of multiplyingS_(k)(i) prior to the DFT operation as shown in FIG. 12 . As describedabove, the above two processes may produce exactly the same result.

FIG. 9 is a block diagram illustrating a configuration of a terminal 900according to another embodiment of the present invention.

Referring to FIG. 9 , the terminal 900 may include a receiver 910, acontroller 920, and a transmitter 930.

The receiver 910 may receive control information and data using aplurality of downlink CCs.

The controller 920 may determine an uplink channel element included inan uplink CC, based on an index of a channel element used to transmitthe control information among a plurality of downlink channel elementsincluded in a downlink CC.

The transmitter 930 may transmit, to a base station 940, ACK/NACK withrespect to the data using the determined uplink channel element.

Scheduling information associated with the data in the controlinformation may be transmitted using a PCC among the plurality ofdownlink CCs. In this case, the receiver 910 may receive the schedulinginformation using the PCC among the plurality of downlink CCs. Thecontroller 920 may determine an uplink channel element in an uplink CCcorresponding to the PCC.

The receiver 910 may receive correspondence relationship between theplurality of downlink CCs and the plurality of uplink CCs. The receiver910 may receive the correspondence relationship using RRC signaling.

Scheduling information associated with the data may be distributed toeach of the downlink CCs and thereby be transmitted. In this case, thereceiver 910 may receive the scheduling information using all of thedownlink CCs. Scheduling information transmitted using a predetermineddownlink CC may relate to data transmitted the corresponding downlinkCC.

Even in this case, ACK/NACK associated with data transmitted using eachdownlink CC may be transmitted using a predetermined single uplink CC.

When ACK/NACK associated with data transmitted using the plurality ofdownlink CCs is transmitted using the single uplink CC, the uplink CCmay need to additionally assign a radio resource.

According to an aspect, in this case, the controller 920 may determinean additional uplink channel element using a downlink channel elementhaving a second lowest index among downlink channel elements used totransmit control information. The transmitter 930 may transmit theACK/NACK using the determined uplink channel element.

The receiver 910 may receive RRC signaling from the base station 940.The RRC signaling may include information associated with apredetermined uplink channel element. In this case, the controller 920may determine an additional uplink channel element based on informationassociated with the predetermined uplink channel element included in theRRC signaling, in order to transmit the ACK/NACK.

According to another embodiment of the present invention, the terminal900 may effectively control a power of an uplink control channel.

The receiver 910 may receive data from the base station 940. Thecontroller 920 may generate ACK/NACK associated with the received data.The transmitter 930 may transmit, to the base station 940, a data packetincluding the ACK/NACK and a scheduling request for the base station940.

In this case, the transmitter 930 may determine a transmit power of thedata packet based on a number of bits of the ACK/NACK and a number ofbits of the scheduling request that are included in the data packet.

The transmitter 930 may determine the transmit power of the data packetaccording to Equation 1:P _(PUCCH)(i)=min{P _(CMAX) ,P _(0_PUCCH) +PL+h(n _(HARQ) ,n_(SR)+Δ_(PUCCH)(F)+g(i)}  [Equation 1]

In Equation 1, P_(CMAX) denotes a maximum transmit power that is aconfigured UE transmitted power of the transmitter 930, and P_(0_PUCCH)is given as a sum of a cell unique parameter P_(O_NOMINAL_PUCCH) and aUE unique parameter P_(O_UE_PUCCH) P_(O_NOMINAL_PUCCH) andP_(O_UE_PUCCH) correspond to parameters provided from an upper layer. PLdenotes an estimate value of a downlink pathloss from the base station940 to the terminal 900. Δ_(F_PUCCH)(F) may be provided from the upperlayer as a value corresponding to a PUCCH format F transmitting thescheduling request for the base station 940, and denotes a relativevalue with respect to a PUCCH format 1a. g(i) corresponds to a valueadjusted by a Transmit Power Control (TPC) command and denotes a currentPUCCH power control adjustment state.

Here, h(n_(HARQ),n_(SR)) may be determined according to Equation 2:

$\begin{matrix}{{h\left( {n_{HARQ},n_{SR}} \right)} = {10{\log_{10}\left( \frac{n_{HARQ} + n_{SR}}{\beta} \right)}}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

In Equation 2, β denotes a proportional constant and β=1. In addition,n_(HARQ) denotes the number of bits of the ACK/NACK, and n_(SR) denotesthe number of bits of the scheduling request.

As one example of β as the proportional constant, β=1 may be used.

Hereinafter, a method proposed in the present invention in order to setn_(HARQ) will be described.

It may be assumed that a number of downlink configured CCs of apredetermined UE is L, a number of activated CCs among the downlinkconfigured CCs is M, and a number of downlink CCs used to transmitdownlink data to the UE based on the determination of the UE is N. Forexample, even though an eNB transmits data to the UE using threedownlink CCs, the UE may not appropriately detect a portion of downlinkassignment information and thus, may determine that the UE has receivedthe data using only two downlink CCs. In this case, N indicates 2.

In a subframe where a scheduling request resource is assigned, whenACK/NACK and scheduling request information are simultaneouslytransmitted using PUCCH format 3, n_(SR)=1. In a subframe where thescheduling request resource is not assigned, n_(SR)=0.

Here, it may be assumed that a number of bits of ACK/NACK to be fed backfrom the UE to the eNB with respect to data received using N downlinkCCs is K. When all of the ACK/NACK is indicated and thereby istransmitted, K may match a total number of transport blocks received atthe terminal. However, when bundling is applied with respect to aportion of or all of ACK/NACK, K may be less than a total number oftransport blocks received at the terminal.

When K=0, the transmission itself may not be performed.

Method 1 for setting n_(HARQ)

n_(HARQ) may be set as follows:n _(HARQ) =K

From information obtained by receiving PDCCHs, the terminal may be awareof a number of transport blocks transmitted to the terminal. In the caseof semi-persistent scheduling (SPS), only a downlink PDSCH transmissionmay be present without a PDCCH transmission from the base station.Accordingly, a total number of transport blocks may need to becalculated by considering the above case. However, the terminal may failin successfully receiving a PDCCH transmitted from the base station. Inthis case, the terminal may transmit information using a smaller amountof power than an appropriate amount of power. Accordingly, the basestation may not successfully detect information. To complement the aboveproblem, the following method may be considered.

Method 2 for setting n_(HARQ)

It may be assumed that downlink CCs that correspond to activated CCs,however, do not have downlink data transmission are c(1), c(2),L,c(M−N), an d a maximum number of ACK/NACK bits probable based on atransmission mode set in a CC c(i) is Q_(c(i)). The proposed method mayset n_(HARQ) as follows:

$n_{HARQ} = {K + {\sum\limits_{i = 1}^{M - N}Q_{c{(i)}}}}$

Even though the terminal determines that data transmission is absent ina n activated CC, a maximum number of ACK/NACK bits transmittable in acorresponding CC may be included in a payload and thereby be calculated.The terminal may fail in receiving a PDCCH and thus, an amount of powermay be set for preparation thereto.

Method 3 for setting n_(HARQ)

It may be assumed that a maximum number of transport blockstransmittable using each downlink CC is a. In a 3GPP LTE TechnicalSpecification Re lease 10, maximum two transport blocks may betransmitted using each downlink CC. Accordingly, in this case, aindicates 2. The proposed method may set n_(HARQ) as follows:n _(HARQ) =K+α(M−N)

Method 4 for setting n_(HARQ)

It may be assumed that downlink CCs that correspond to downlinkconfigured CCs, however, do not have downlink data transmission ared(1), d(2),L, d(L−N) and a maximum number of ACK/NACK bits probablebased on a transmission mode set in a CC d(i) is Q_(d)(i). The proposedmethod may set n_(HARQ) as follows:

$n_{HARQ} = {K + {\sum\limits_{i = 1}^{L - N}Q_{d{(i)}}}}$

Method 5 for setting n_(HARQ)

The proposed method may set n_(HARQ) as follows:n _(HARQ) =K+α(L−N)

FIG. 10 is a block diagram illustrating a configuration of a terminal1000 according to still another embodiment of the present invention.

Referring to FIG. 10 , the terminal 1000 may include a receiver 1010, anACK/NACK generator 1020, a controller 1030, an encoder 1040, and atransmitter 1050.

The receiver 1010 may receive, from a base station 1060, informationassociated with downlink CCs available from communication between theterminal 1000 and the base station 1060. Also, the receiver 1010 mayreceive a data block using a portion of or all of data receiving CCsamong the downlink CCs.

The base station 1060 may assign, to the terminal 1000, a portion ofdata receiving CCs among the downlink CCs available by the base station1060 and thereby, activate the assigned data receiving CCs. The basestation 1060 may select a portion of the activated downlink CCs, and maytransmit data using the selected downlink CC.

The receiver 1010 may receive downlink CC assignment information fromthe base station 1060. The ACK/NACK generator 1020 may detect a datablock with respect to the downlink CC assigned to the terminal 1000.

With respect to a downlink CC unassigned to the terminal 1000, theACK/NACK generator 1020 may generate DTX as ACK/NACK. Also, the ACK/NACKgenerator 1020 may determine that a downlink CC assigned to the terminal1000, however, in which a PDCCH containing data scheduling informationis not detected is not assigned to the terminal 1000.

Also, with respect to the downlink CC assigned to the terminal 1000,when the data block is successfully received, the ACK/NACK generator1020 may generate ACK as the ACK/NACK. Conversely, when the data blockis not successfully received, the ACK/NACK generator 1020 may generateNACK as the ACK/NACK.

Specifically, the ACK/NACK generator 1020 may generate ACK/NACK withrespect to all of downlink CCs available at the base station 1060.

The ACK/NACK generator 1020 may determine a number of data blockstransmitted using each downlink CC based on a transmission mode of thebase station 1060, and may generate ACK/NACK with respect to each of thedata blocks.

The base station 1060 may transmit a data block according to a generaldata transmission scheme, for example, a non-MIMO transmission scheme,and may also transmit data using a MIMO transmission scheme.

When the base station 1060 is set to a MIMO transmission mode oftransmitting data using the MIMO transmission scheme, the receiver 1010may receive two data blocks using a single subframe included in a singledata receiving CC.

When the base station 1060 is set to a non-MIMO transmission mode oftransmitting data using the general data transmission scheme, forexample, the non-MIMO transmission scheme, the receiver 1010 may receivea single data block using a single subframe included in a single datareceiving CC.

Hereinafter, a procedure of generating, by a terminal, ACK/NACK will bedescribed.

Configuration: A base station may notify each terminal of a downlink CCand an uplink CC to be used for communication between the base stationand a corresponding terminal. The base station may notify each terminalof a transmission mode of each of configured CCs using an RRC message.

Activation: The base station may notify each terminal of a downlink CCand an uplink CC to be directly used for communication between the basestation and a corresponding terminal. In this instance, a Media AccessControl (MAC) message may be used. A downlink CC to be activatedcorresponds to a subset of downlink CCs configured as the configuration.The base station may perform downlink assignment only with respect toCCs belonging to an activated CC set of the terminal.

Setting of a PDCCH monitoring set: In the case of a terminal using aCIF, the base station may set the terminal to detect a PDCCH only withrespect to a predetermined downlink CC. Downlink CCs for which theterminal is set to detect a predetermined PDCCH are referred to as thePDCCH monitoring set. The PDCCH monitoring set corresponds to a subsetof activated downlink CCs.

The terminal may generate ACK/NACK as follows:

A terminal not using a CIF may detect a PDCCH search space in all ofactivated downlink CCs and thereby, verify whether a PDCCH is assignedto the terminal.

When a PDCCH monitoring set is set, a terminal using the CIF may detectthe PDCCH search space with respect to only a corresponding downlink CCand thereby, verify whether the PDCCH is assigned to the terminal. Evenin the case of the terminal using the CIF, when the PDCCH monitoring setis not set, the terminal may detect the PDCCH search space with respectto all of activated downlink CCs and thereby, verify whether any PDCCHis assigned to the terminal.

A set of activated CCs S_activation may be assumed to be configured as NCCs as follows:S_activation={CC₀,CC₁, . . . , CC_(N−1)}

Here, CC_(i) needs to be an element of a set of configured CCsS_configuration, i.e., CC_(i)∈S_configuration. Here, i=0,1, . . . , N−1.

1. Generating of ACK/NACK Based on a Set of Activated Downlink CCs:

The terminal may generate ACK/NACK based on the set of activateddownlink CCs. Specifically, the terminal may configure ACK/NACK withrespect to each CCi and then collect the configured ACK/NACK to therebyconfigure ACK/NACK with respect to N CCs of the activated downlink CCs.In general, downlink assignment information received at the terminalrelates to all of activated downlink CCs or a subset thereof. However,ACK/NACK generated by the terminal may be with respect to all ofactivated downlink CCs. It may be assumed that the terminal hasattempted PDCCH detection in a predetermined subframe and verifieddownlink assignment with respect to M CCs (M>0) as follows:

Set of downlink assigned CCs S_assignment={DA0, . . . DAM−1}

When predetermined CCi belongs to the set of downlink assigned CCs,i.e., when CC_(i)∈S_assignment, ACK/NACK signal Signal_CC_(i) withrespect to CCi may be generated as follows:

When CC_(i)∈S_assignment,

when a single transport block is transmitted via CC_(i),Signal_CC_(i)=ACK or NACK.

When two transport blocks are transmitted via CC_(i),Signal_CC_(i)=ACK_ACK, ACK_NACK, NACK_ACK or NACK_NACK.

Here, ACK indicates that a corresponding transport block is successfullyreceived and NACK indicates that the transport block is not successfullyreceived. ACK_ACK, ACK_NACK, NACK_ACK, NACK_NACK, and the like mayindicate whether a first transport block and a second transport blockare successfully received or not.

When CC_(i)∉S_assigmnent, no assignment may be indicated in ACK/NACKsignal Signal_CCi with respect to CCi as follows:

When CC_(i)∉S_assignment, Signal_CC_i=DTX.

Accordingly, ACK/NACK Signal with respect to downlink data with whichthe terminal is assigned in a predetermined subframe may be indicated asfollows:Signal={Signal_CC₀, . . . Signal_CC_(N−1)}

In this instance, when the terminal attempted the PDCCH detection in apredetermined subframe, however, no downlink assignment is detected,i.e., when M=0, the terminal may not transmit any ACK/NACK signal.Specifically, when Signal_CC_(i)=DTX with respect to i=0, 1, . . . N−1,the terminal may not transmit the ACK/NACK signal itself.

In the case of the above scheme, even with respect to a CC with whichthe terminal is not assigned in a predetermined single subframe, whenthe CC belongs to a set of activated CCs, no assignment DTX may beindicated in the ACK/NACK signal.

A method of transmitting, by the terminal, an ACK/NACK signal withrespect to only an assigned CC may be considered. However, in this case,a confusion may occur between the terminal and the base station. Eventhough the base station attempts a downlink assignment by transmitting aPDCCH, the terminal may fail in receiving the PDCCH. When the terminalfails in receiving the PDCCH, whether the base station has transmittedthe PDCCH may not be verified and thus, the base station may be regardedto not have transmitted the PDCCH. In this case, ACK/NACK transmittedfrom the terminal may be with respect to only a CC succeeding inreceiving the PDCCH. Accordingly, the base station may not appropriatelydetermine whether ACK/NACK transmitted from the terminal is generated asa result of successfully receiving all of PDCCHs transmitted from thebase station, or by successfully receiving only a portion of the PDCCHs.Consequently, the base station may not appropriately verify ACK/NACKtransmitted from the terminal.

In the case of using the aforementioned scheme, when it is assumed thatthe terminal and the base station have a mutually matched understandingwith respect to a set of activated CCs, the terminal may generateACK/NACK with respect to all of the activated CCs at all times.Accordingly, the base station may obtain ACK/NACK without any confusion.

A variety of schemes described in subclause 1.2 may be considered as atransmission scheme for a terminal to transmit ACK/NACK. When each ofall cases indicated by ACK/NACK Signal={Signal_CC0, . . . Signal_CCN−1}is mapped to a different transmission form and thereby is transmitted,the base station may find ACK/NACK corresponding to the receivedtransmission form.

For example, when a terminal set to not use a MIMO transmission schemegenerates ACK/NACK with respect to two CCs, nine cases of ACK/NACK maybe generated as shown in the following table. In the table, a last linecorresponds to a case where the terminal detects no assignment withrespect to all of two CCs. In this case, the terminal may not transmitany ACK/NACK signal. Accordingly, each of eight cases where the terminaltransmits an ACK/NACK signal may be transmitted in a differenttransmission form and thereby, be identified by the base station.

In general, when the terminal indicates ACK/NACK with respect to N CCs,and when a number of cases of ACK/NACK that the terminal needs toexpress with respect to a single CC_(i) is L_(i), a total number ofcases that the terminal needs to express through a signal transmissionmay become L₀×L₁× . . . ×L_(N−1)−1. Here, −1 is to exclude a case wherethe terminal does not receive any assignment with respect to all of NCCs. Accordingly, the base station and the terminal may need to promisein advance transmission forms that make a one-to-one correspondence withrespect to (L₀×L₁× . . . ×L_(N−1)−1) cases of ACK/NACK. In the case of asingle transport block, cases of ACK, NACK, and DTX may exist and thus,L_(i)=3. In the case of two transport blocks, cases of ACK_ACK,ACK_NACK, NACK_ACK, NACK_NACK, and DTX may exist and thus, L_(i)=5.

According to the aforementioned ACK/NACK transmission scheme, cases of achannel selection, a resource selection, a sequence selection, and thelike may need to make a one-to-one correspondence with respect to casesof ACK/NACK where each case of a selected channel, resource, sequence,and the like is different. When ACK/NACK is expressed using a bit like aDFT-S OFDM, the ACK/NACK may be expressed as log₂┌L₁× . . . ×L_(N−1)−1┐bits. Table 39 shows a number of cases of ACK/NACK according tocombinations of ACK/NACK values.

TABLE 39 Signal_CC₀ Signal_CC₁ 1 ACK ACK 2 ACK NACK 3 ACK DTX 4 NACK ACK5 NACK NACK 6 NACK DTX 7 DTX ACK 8 DTX NACK 9 DTX DTX

2. Generation of ACK/NACK Based on a Set of Downlink Configured CCs:

When there is a probability that a terminal and a base station may nothave the mutually same understanding regarding the set of activated CCs,a method of generating information based on the set of downlinkconfigured CCs may be used when the terminal generates ACK/NACK.Regarding a CC with assignment, this method may generate ACK/NACK usingthe same scheme as the aforementioned scheme of generating ACK/NACKbased on the set of activated downlink CCs. Regarding a CC withoutassignment, when the CC belongs to a set of configured CCs, the terminalmay indicate no assignment in an ACK/NACK signal.

A set of configured CC S_configuration may be assumed to be indicated asfollows:S_configuration={CC₀, . . . , CC_(K−1)}

ACK/NACK Signal in response to downlink data in a subframe with whichthe terminal is assigned may be indicated as follows:Signal={Signal_CC₀, . . . Signal_CC_(K−1)}

Here, Singal_CC_(i) corresponds to ACK/NACK with respect to downlink CCCC_(i).

The terminal may need to generate the ACK/NACK Signal based on atransmission mode of each of downlink CCs belonging to the set ofconfigured CCs.

When a single transport block is transmitted via CC_(i),Signal_CC_(i)=ACK or NACK.

When two transport blocks are transmitted via CC_(i),Signal_CC_(i)=ACK_ACK, ACK_NACK, NACK_ACK or NACK_NACK.

When CC_(i)∉S_assignment, no assignment may be indicated in ACK/NACKsignal Signal_CCi as follows:

When CC_(i)∉S_assignment, Signal_CC_i=DTX.

Here, when NACK and DTX are not discriminated from each other, NACK andDTX may be regarded as the same state. Accordingly, when the singletransport block is transmitted via CC_(i), Signal_CC_(i)=ACK orNACK/DTX.

When two transport blocks are transmitted via CC_(i),Signal_CC_(i)=ACK_ACK, ACK_(NACK/DTX), (NACK/DTX)_ACK or(NACK/DTX)_(NACK/DTX).

In a DFT-S-OFDM based ACK/NACK transmission scheme, input bits of achannel encoder may be ACK/NACK bits. Hereinafter, a method ofgenerating ACK/NACK bits will be described.

Method 1: Method of Generating ACK/NACK Based on a Transmission Mode forEach CC:

For example, it may be assumed that the terminal is set to have Ndownlink configured CCs, some of N downlink configured CCs are set to aMIMO transmission mode in which the terminal may transmit maximum twotransport blocks and remaining CCs are set to a non-MIMO transmissionmode in which the terminal may transmit a single transport block. Inaddition, it may be assumed that a NACK state and a DTX state are notdiscriminated from each other. Based on downlink assignment informationreceived at the terminal, the number of transport blocks receivable atthe terminal in a subframe may be zero, one, or two for each CC. A casewhere the number of transport blocks is zero corresponds to a case wherethe base station does not perform downlink assignment, or a case wherethe base station performs downlink assignment, however, the terminaldoes not appropriately receive the assignment information. Here, theterminal may generate ACK/NACK bits for all of the configured CCs at alltimes and may indicate ACK/NACK state based on the transmission modes ofindividual CCs. For example, in the case of a CC with which the numberof assigned transport blocks is zero, if the CC is configured with aMIMO transmission mode, NACK/DTX may be indicated for each of twotransport blocks using two bits. If the CC is configured with a non-MIMOtransmission mode, NACK/DTX may be indicated using a single bit. Even ifa single transport block is assigned to a corresponding subframe in a CCconfigured with the MIMO transmission mode, information may be indicatedbased on the maximum number of transport blocks receivable in thecorresponding CC. Accordingly, ACK or NACK/DTX may need to be indicatedusing two bits with respect to each of two transport blocks.

Specifically, ACK/NACK bit values with respect to CC_(i) may beindicated as in Table 40 or Table 41 based on the configuredtransmission mode. In the tables, DTX indicates that the terminal hasnot received downlink assignment information of a corresponding CC.Specifically, this may correspond to a case where the base station doesnot perform assignment with respect to the CC and thus, the terminaldoes not receive assignment information, or to a case where the basestation transmits assignment information through a PDCCH, however, theterminal fails in receiving the assignment information. Regardless ofwhether the assignment information is received, the terminal needs togenerate ACK/NACK bits with respect to all configured CCs. Accordingly,all of CCs belonging to configured CCs, however, of which assignmentinformation is not received may be indicated as DTX. Table 40 showsgeneration of ACK/NACK bits of CC_(i) set to the MIMO transmission mode.Table 41 shows generation of ACK/NACK bits of CC_(i) configured with anon-MIMO transmission mode.

TABLE 40 generation of ACK/NACK bits of CC_(i) configured with a MIMOtransmission mode First Second transport block transport block b_(i)(0),b_(i)(1) ACK ACK 1, 1 ACK NACK 1, 0 NACK ACK 0, 1 NACK NACK 0, 0 DTX 0,0

TABLE 41 generation of ACK/NACK bits of CC_(i) configured with anon-MIMO transmission mode Transport block b_(i)(0) ACK 1 NACK 0 DTX 0

For example, when the terminal is configured to have five downlinkconfigured CCs, and CC₀, CC₁, and CC₂ are set to be in a MIMOtransmission mode, and CC₃ and CC₄ are set to be in a non-MIMOtransmission mode, the ACK/NACK bits may include a total of (2+2+2+1+1=)8 bits.

To maintain a consistent signal transmitting/receiving system matchedbetween the terminal and the base station, the terminal may indicate anACK/NACK state based on a transmission mode configured for eachconfigured CC. Even though the base station transmits assignmentinformation with respect to a downlink CC through a PDCCH, the terminalmay not receive the assignment information. Accordingly, when theterminal transmits information with its magnitude varying depending onwhether the assignment information is received, the base station may beunaware of whether the terminal has successfully received the assignmentinformation and thus, it may be difficult to demodulate an ACK/NACKsignal transmitted from the terminal and thereby obtain accurateinformation. For the above reason, the terminal may need to indicate anACK/NACK state based on a set transmission mode at all times regardlessof whether the assignment information is received.

If the ACK/NACK bit mapping method described in the aforementionedembodiment is used, the base station may not be able to discriminateNACK and DTX states. To enable the base station to identify whether theterminal has successfully received downlink grant PDCCH when the basestation transmits a single transport block in a CC where the terminal isset to the MIMO transmission mode, a different ACK/NACK bit mapping maybe used to indicate DTX. A CC set to a Single Input Multiple Output(SIMO) transmission mode may generate ACK/NACK as shown in Table 41,using a single bit. This is the same as the aforementioned case. The CCset to the MIMO transmission mode may indicate ACK/NACK using two bits,regardless of the number of actually received transport blocks. When theterminal receives a single transport block, ACK/NACK bits may begenerated as shown in Table 45. When the terminal actually receives twotransport blocks, ACK/NACK bits may be generated as shown in Table 46.When the terminal determines that a PDSCH transmission is absent in theCC set to the MIMO transmission mode, ACK/NACK bits may be generated asshown in Table 47. When such ACK/NACK bit mapping is used, the basestation can identify all three states of ACK, NACK, and DTX when thebase station transmits a single transport block. Specifically, the keypoint of ACK/NACK bit mapping lies in that in the case of a CC set tothe MIMO transmission mode, ACK, NACK, and DTX are expressed usingdifferent bit values with respect to the single transport block. Becausethe base station knows whether the base station has transmitted a singletransport block or two transport blocks, the base station is aware ofwhich mapping should be applied between Table 45 and Table 46. Thus, inthe case of transmission of a single-transport block, the base stationcan distinguish ACK, NACK, and DTX by referring to Table 45 and Table47.

Method 2: Method of Generating ACK/NACK Based on a Maximum TransportBlock Mode of Each CC:

The transmission mode of each CC configured for a terminal can bechanged by RRC signaling. In this case, a matched understandingregarding the transmission mode may be absent between the terminal andthe base station for a certain time interval. To solve the aboveproblem, the terminal may need to indicate an ACK/NACK state based on aprobable maximum transport block mode for each CC at all times. Forexample, it may be assumed that a terminal having a MIMO receptioncapability is configured to have five downlink CCs, and a portion of thefive downlink CCs are set to a MIMO transmission mode capable oftransmitting maximum two transport blocks and remaining downlink CCs areset to a non-MIMO transmission mode capable of transmitting a maximumsingle transport block. In addition, it may be assumed that NACK and DTXare not discriminated from each other. In this case, even with respectto a CC set to the non-MIMO transmission mode, the terminal may indicatean ACK/NACK state using two bits at all times. That is, even though theCC is set to the non-MIMO transmission mode, ACK/NACK may be generatedusing two bits as shown in Table 40. Through this, even in a timeinterval where a transmission mode varies by a reconfiguration of atransmission mode, a configuration of ACK/NACK between the terminal andthe base station may not vary and thus, the base station may demodulatean ACK/NACK signal and thereby obtain accurate information.

Specifically, when the terminal has a MIMO reception capability, thatis, when the terminal may receive maximum two transport blocks for eachCC, ACK/NACK may be generated using two bits with respect to each ofdownlink CCs based on the above criterion. Accordingly, when a number ofconfigured CCs is N, a total number of ACK/NACK bits generated by theterminal may become 2N. When the terminal does not have a MIMO receptioncapability and has only a SIMO reception capability, that is, when theterminal may receive a maximum single transport block, ACK/NACK may begenerated using a single bit with respect to each of configured CCsbased on the above criterion. Accordingly, when the number of configuredCCs is N, a total number of ACK/NACK bits generated by the terminal maybecome N.

Hereinafter, methods of generating ACK/NACK bits will be described

1) A Case where the Terminal does not have a MIMO Reception Capability:

Since the terminal may receive only a maximum single transport block, amaximum transport block of each configured CC may be the same as one.

Method A: As shown in Table 42, ACK/NACK of a single transport block maybe expressed using a single bit. In method A, an NACK state and ano-PDSCH transmission state may be mapped to the same bit value.

Method B: As shown in Table 43, ACK/NACK of a single transport block maybe expressed using two bits. In method B, an NACK state and a no-PDSCHtransmission state may be mapped to different bit values, so that thebase station may discriminate the NACK state from the no-PDSCHtransmission state.

TABLE 42 indication of ACK/NACK bit value of CC_(i) when a maximumsingle transport block is received in method A Transport block stateb_(i)(0) ACK 1 NACK 0 No PDSCH transmission (DTX) 0

TABLE 43 indication of ACK/NACK bit value of CC_(i) when a maximumsingle transport block is received in method B Transport block stateb_(i)(0), b_(i)(1) ACK 1, 0 (or 1, 1) NACK 0, 1 No PDSCH transmission(DTX) 0, 0

2) A Case where the Terminal has a MIMO Reception Capability:

In this case, the terminal may receive maximum two transport blocks foreach configured CC. As described above, ACK/NACK may be expressed usingtwo bits for each CC regardless of a transmission mode of each CC. Table44 shows an example of ACK/NACK indication in a CC set to the SIMOtransmission mode capable of receiving a maximum single transport block.

TABLE 44 example of ACK/NACK bit mapping of CC_(i) set to SIMOtransmission model Transport block state b_(i)(0), b_(i)(1) ACK 1, 0 (or1, 1) NACK 0, 1 No PDSCH transmission (DTX) 0, 0

TABLE 45 example of ACK/NACK bit mapping of CC_(i) set to MIMOtransmission mode: case where terminal substantially receives a singletransport block Transport block state b_(i)(0), b_(i)(1) ACK 1, 0 (or1, 1) NACK 0, 1

TABLE 46 example of ACK/NACK bit mapping of CC_(i) set to MIMOtransmission mode: case where terminal substantially receives twotransport blocks First transport Second transport block state blockstate b_(i)(0), b_(i)(1) ACK ACK 1, 1 ACK NACK 1, 0 NACK ACK 0, 1 NACKNACK 0, 0

Table 47 shows an ACK/NACK bit value when the terminal determines that aPDSCH transmission is absent in a CC set to the MIMO transmission mode.

TABLE 47 example of ACK/NACK bit value mapping of CC_(i) set to MIMOtransmission mode: case where terminal determines that downlink PDSCHtransmission is absent by including SPS PDSCH transmission b_(i)(0),b_(i)(1) No PDSCH transmission (DTX) 0, 0

What is important in the above scheme, both a case where the terminaldetermines that a PDSCH transmission is absent with respect to CC_(i)and a case where the terminal receives two transport blocks, however,detects NACK with respect to all of the transport blocks may need to beexpressed using the same bit value. In the above example, (b_(i)(0),b_(i)(1))=(0, 0). The above bit value mapping corresponds to oneembodiment. Another type of bit mapping may be employed. However, it maybe desirable to express, using the same bit value, both the case wherethe terminal determines that the PDSCH assignment is absent with respectto CC_(i) and the case where the terminal receives two transport blocks,however, detects NACK with respect to all of the transport blocks. Thisis to enable the base station to be aware of a circumstance that thebase station has transmitted a single transport block via a downlinkgrant so that the terminal may receive the single transport block,however, the terminal has not successfully received the downlink grant.The base station may effectively control a power of a PDCCH using theabove information.

However, when resetting of a transmission mode barely occurs, or whenresetting of the transmission mode is constrained, the terminal mayemploy a scheme of indicating an ACK/NACK state based on a transmissionmode set for each CC at all times as shown in method 1.

In the above two schemes, when the terminal receives a downlinkassignment with respect to only a single downlink CC and the assigned CCcorresponds to a downlink PCC, the terminal may be assigned with anACK/NACK resource and may perform transmission using the same scheme asLTE Rel-8/9.

Method 3: method of generating ACK/NACK based on a DCI format fordownlink assignment transmitted for each CC:

Method 3 corresponds to a method of indicating ACK/NACK generated by theterminal depending on whether a DCI format transmitted to the terminalcorresponds to a format for a MIMO transmission or a format for a SIMOtransmission. In LTE Rel-8/9, even though the terminal has a MIMOtransmission mode, the base station may transmit a DCI format for a SIMOtransmission by including a fall-back mode. In LTE Rel-8/9, the DCIformat for the SIMO transmission for fall-back corresponds to DCI format1A. Table 48 shows TS36.213 v9.10, Table 7.1-5.

TABLE 48 PDCCH and PDSCH configured by C-RNTI Transmission Transmissionscheme of PDSCH mode DCI format Search Space corresponding to PDCCH Mode1 DCI format 1A Common and Single-antenna port, port 0 (see UE specificby C-RNTI subclause 7.1.1) DCI format 1 UE specific by C-RNTISingle-antenna port, port 0 (see subclause 7.1.1) Mode 2 DCI format 1ACommon and Transmit diversity (see subclause 7.1.2) UE specific byC-RNTI DCI format 1 UE specific by C-RNTI Transmit diversity (seesubclause 7.1.2) Mode 3 DCI format 1A Common and Transmit diversity (seesubclause 7.1.2) UE specific by C-RNTI DCI format 2A UE specific byC-RNTI Large delay CDD (see subclause 7.1.3) or Transmit diversity (seesubclause 7.1.2) Mode 4 DCI format 1A Common and Transmit diversity (seesubclause 7.1.2) UE specific by C-RNTI DCI format 2 UE specific byC-RNTI Closed-loop spatial multiplexing (see subclause 7.1.4) orTransmit diversity (see subclause 7.1.2) Mode 5 DCI format 1A Common andTransmit diversity (see subclause 7.1.2) UE specific by C-RNTI DCIformat 1D UE specific by C-RNTI Multi-user MIMO (see subclause 7.1.5)Mode 6 DCI format 1A Common and Transmit diversity (see subclause 7.1.2)UE specific by C-RNTI DCI format 1B UE specific by C-RNTI Closed-loopspatial multiplexing (see subclause 7.1.4) using a single transmissionlayer Mode 7 DCI format 1A Common and If the number of PBCH antennaports is UE specific by C-RNTI one, Single-antenna port. port 0 is used(see subclause 7.1.1); otherwise Transmit diversity (see subclause7.1.2) DCI format 1 UE specific by C-RNTI Single-antenna port; port 5(see subclause 7.1.1) Mode 8 DCI format 1A Common and If the number ofPBCH antenna ports is UE specific by C-RNTI one, Single-antenna port,port 0 is used (see subclause 7.1.1), otherwise Transmit diversity (seesubclause 7.1.2) DCI format 2B UE specific by C-RNTI Dual layertransrnission; port 7 and 8 (see subclause 7.1.1) or single-antennaport:, port 7 or 8 (see subclause 7.1.1

In Table 48, mode 3, mode 4, and mode 8 correspond to a MIMO modecapable of transmitting maximum two transport blocks. The MIMO mode maybe assigned with a downlink resource through DCI format 1A that is theDCI format for the SIMO transmission, in addition to the DCI format forthe MIMO transmission. Even an LTE-Advance standard may employ the DCIformat for the SIMO transmission for fall-back, which is-similar to LTERel-8/9.

In this method, the terminal may determine a number of ACK/NACK bitsdepending on whether the received DCI format corresponds to a format forthe MIMO transmission or a format for the SIMO transmission. When theDCI format successfully received at the terminal corresponds to the DCIformat for the MIMO transmission, two bits may be used. When thereceived DCI format corresponds to the DCI format for the SIMOtransmission, a single bit may be used.

In the case of the above method, when the terminal does not successfullyreceive the DCI format transmitted from the base station, the terminalmay not determine the number of ACK/NACK bits. For example, when theterminal does not receive downlink assignment information with respectto a predetermined CC, the terminal may not determine whether to expressACK/NACK using a single bit or two bits even though the terminal needsto generate the ACK/NACK indicating DTX/NACK.

When the terminal transmits ACK/NACK in a subframe where a schedulingrequest resource is assigned, the terminal may perform encoding byadding, to a number of ACK/NACK bits, a single bit indicating whether ofa scheduling request. Specifically, when ACK/NACK includes N bits, theterminal may add a single bit of scheduling request information andthereby, use a total of (N+1) bits as an input. Next, after performingRM coding, the terminal may transmit the RM coding result according to aDFT-S-OFDM based ACK/NACK transmission scheme.

When the terminal receives a downlink assignment with respect to only asingle downlink CC in a predetermined subframe, and the assigneddownlink CC corresponds to a downlink PCC, the terminal may be assignedwith an ACK/NACK resource and transmit ACK/NACK using the sametransmission scheme as LTE Rel-8/9. When a PDSCH assignment using adynamic PDCCH is absent in a PCC, however, when an SPS assignment ispresent in the PCC, the terminal may use a persistent ACK/NACK resourcecorresponding to the SPS assignment and may transmit ACK/NACK using thesame resource assignment and transmission format as LTE Rel-8/9.

In the subframe where the scheduling request resource is assigned, inthe case of negative SR, the terminal may transmit ACK/NACK according toRel-8/9 fallback scheme of DFT-S-OFDM ACK/NACK as above. In the case ofpositive SR, the terminal may transmit corresponding ACK/NACK using theassigned scheduling request resource. Specifically, the terminal may usethe same scheme described in the single-carrier Rel-8/9 standard whichis applied when the terminal transmits ACK/NACK and positive SR in thesame subframe.

According to an aspect, the controller 1030 may determine whether ascheduling request resource is assigned to the terminal 1000 in apredetermined subframe. When the scheduling request resource isassigned, the encoder 1040 may encode a scheduling request.

The encoder 1040 may encode the scheduling request and ACK/NACK withrespect to a data block. The transmitter 1050 may transmit, to the basestation 1060, the encoded scheduling request and ACK/NACK.

According to an aspect, when a transmit power is insufficient, due to arelatively poor channel environment, for example, a cell edge and thelike, ACK/NACK bundling may be applied. A base station may set ACK/NACKbundling in a terminal using RRC signaling. The terminal set to theACK/NACK bundling may transmit an ACK/NACK signal by performing ACK/NACKbundling.

The base station may assign a radio resource for ACK/NACK bundling usingRRC signaling. The base station may assign, as the radio resource forACK/NACK bundling, one of radio resources belonging to an uplink PCC.

The base station may also assign a radio resource to the terminal usingan index of a channel element.

Cross-carrier scheduling may not be set with respect to the terminal. Inthis case, the base station may assign the radio resource using a lowestchannel element index in control information assigned to a PCC.

Also, when SPS is assigned, the base station may transmit an ACK/NACKbundling signal using a persistent radio resource corresponding to theSPS assignment.

Cross-carrier scheduling may be set with respect to the terminal. Inthis case, the base station may assign the radio resource using thelowest channel element index in control information assigned to the PCC.Also, the base station may assign the radio resource using a highestchannel element index in control information received using another CC.

The terminal may transmit, to the base station, a number of downlink CCsof which a PDSCH is successfully received in a subframe where downlinkassignment information is transmitted. The base station may determine atransmission using which CC is successfully performed based on thenumber of downlink CCs of which the PDSCH is successfully received.

When two data blocks are assigned within an assigned uplink CC, theterminal may perform ACK/NACK bundling. When two data blocks arereceived, ACK/NACK bundling may obtain ACK/NACK bits with respect toeach data block through a logic operation ‘AND’.

FIG. 11 is a block diagram illustrating a configuration of a terminal1100 according to yet another embodiment of the present invention.

The terminal 1100 may include a transmitter 1110.

The transmitter 1110 may transmit, to a base station 1120, a subframeincluding a first slot and a second slot. Each of the first slot and thesecond slot may include a cyclic shift.

According to an aspect, a first cyclic shift included in the first slotmay be different from a second click shift included in the second slot.In this case, interference between terminals transmitting controlinformation to a base station may be randomized.

The transmitter 1110 may change a first cyclic shift for each subframe.When the first cyclic shift is changed, a second cyclic shift may alsobe changed to be different from the first cyclic shift.

According to an aspect, a base station may receive data from a pluralityof terminals. In this case, interference may occur between the datareceived from the plurality of terminals. For example, when a firstterminal transmits a first slot and a second slot, and a second terminaltransmits a third slot and a fourth slot, the first slot may interferewith the third slot transmitted in the same time zone. The second slotmay interfere with the fourth slot transmitted in the same time zone.

Based on interference between the first cyclic shift included in thefirst slot and the third cyclic shift included in the third slot, thesecond cyclic shift included in the second slot and the fourth cyclicshift included in the fourth slot may be determined.

For example, when a DFT sequence is used as a cyclic shift, theorthogonality may be further maintained as sequence indices is furtherseparate from each other. Accordingly, when two terminals useneighboring sequences as a cyclic shift in the first slot, the terminalsmay determine separate sequences as a cyclic shift in the second slot.According to the above embodiment, most interfering terminals may beappropriately distributed in the first slot and the second slot, wherebyan amount of interference may be normalized.

The base station may transmit a single transport block using a pluralityof downlink CCs. In this case, it is possible to guarantee a relativelyexcellent data rate even for a terminal with a relatively poor channelenvironment, for example, a cell edge and the like.

According to an aspect, a base station may repeat the same transmissionwith respect to a plurality of downlink CCs. That is, the base stationmay transmit the same transport block using the exactly same amount ofresources and a transmission format, for example, a Modulation andCoding Scheme (MCS) and the like. This may be referred to as a‘frequency domain loop transmission of downlink CC level’.

When the terminal combines the received data using a plurality ofdownlink CCs, a receive power and a diversity may increase whereby areception quality may be enhanced. The terminal may demodulate anddecode a transport block generated by combining the data, and mayperform a CRC, and then may transmit a corresponding result using asingle ACK/NACK symbol.

Data transmitted using each CC may form a single codeword. That is, datatransmitted using a single CC may be self-decodable. This is to decreasea complexity between the terminal and the base station by mapping asingle codeword to a single CC at all times in all the cases ofincluding the aforementioned ‘frequency domain loop transmission ofdownlink CC level’.

According to another aspect, a different form of a codeword with respectto the same transport block may be allowable to different CCs. Forexample, a transmission scheme used for retransmission in a time domainmay be used for a different CC of a frequency domain. This method is toallow all the transmission formats used for HARQ retransmission to beavailable for loop transmission of the CC level.

The above loop transmission of the CC level through the same codewordtransmission may be a special example of the above method.

The terminal may receive a downlink grant in the same form as a downlinkgrant using a CIF or a downlink grant not using the CIF. ACK/NACK withrespect to a received transport block is a single symbol and thus, theterminal may transmit the ACK/NACK using a single uplink CC. In thisinstance, the terminal may select a resource corresponding to apredetermined PDCCH from resources defined in LTE Rel-8 and thereby,transmit the ACK/NACK using the selected resource.

Although a few embodiments of the present invention have been shown anddescribed, the present invention is not limited to the describedembodiments. Instead, it would be appreciated by those skilled in theart that changes may be made to these embodiments without departing fromthe principles and spirit of the invention, the scope of which isdefined by the claims and their equivalents.

What is claimed is:
 1. A communication method, the method comprising:generating, by a user equipment (UE), a set of bits based onretransmission information; generating, by the UE, a first set ofcomplex-valued symbols based on the set of bits; determining, by the UE,one of a first set of orthogonal sequences; determining, by the UE, afirst complex number; multiplying, by the UE, one of the first set ofcomplex-valued symbols with an element of the one of the first set oforthogonal sequences and the first complex number to generate a firstsymbol; generating, by the UE, a second symbol based on a referencesignal sequence; generating, by the UE, a subframe comprising a firstslot and a second slot, wherein the first slot comprises a plurality ofsymbols, including the first symbol and the second symbol; andtransmitting, by the UE, the subframe to a base station, wherein: thefirst complex number is determined based on a slot number of the firstslot and a symbol number of the first symbol.
 2. The communicationmethod of claim 1, further comprising: determining, by the UE, an index,wherein the one of the first set of orthogonal sequences is determinedbased on the index.
 3. The communication method of claim 1, wherein thefirst complex number is determined also based on a cell identifier (cellID).
 4. The communication method of claim 1, further comprising:determining, by the UE, another of the first set of orthogonalsequences; determining, by the UE, a second complex number; andmultiplying, by the UE, another of the first set of complex-valuedsymbols with an element of the another of the first set of orthogonalsequences and the second complex number to generate a third symbol,wherein: the second slot comprises a plurality of symbols, including thethird symbol, and the second complex number is determined based on aslot number of the second slot and a symbol number of the third symbol.5. The communication method of claim 4, wherein the first complex numberand the second complex number has a same amplitude.
 6. The communicationmethod of claim 2, wherein the one of the first set of orthogonalsequences is determined based on the index and Table 1 TABLE 1 IndexFirst set of orthogonal sequences 0 [1 1 1 1 1] 1 [1 e^(j2π/5) e^(j4π/5)e^(j6π/5) e^(j8π/5)] 2 [1 e^(j4π/5) e^(j8π/5) e^(j12π/5) e^(j16π/5)] 3[1 e^(j6π/5) e^(j12π/5) e^(j18π/5) e^(j24π/5)] 4 [1 e^(j8π/5) e^(j16π/5)e^(j24π/5) e^(j32π/5)].


7. A user equipment (UE), comprising: circuitry which is configured to:cause the UE to generate a set of bits based on retransmissioninformation; cause the UE to generate a first set of complex-valuedsymbols based on the set of bits; determine one of a first set oforthogonal sequences; determine a first complex number; multiply one ofthe first set of complex-valued symbols with an element of the one ofthe first set of orthogonal sequences and the first complex number togenerate a first symbol; cause the UE to generate a second symbol basedon a reference signal sequence; cause the UE to generate a subframecomprising a first slot and a second slot, wherein the first slotcomprises a plurality of symbols, including the first symbol and thesecond symbol; and cause the UE to transmit the subframe to a basestation, wherein: the first complex number is determined based on a slotnumber of the first slot and a symbol number of the first symbol.
 8. TheUE of claim 7, wherein the circuitry is further configured to: determinean index, wherein the one of the first set of orthogonal sequences isdetermined based on the index.
 9. The UE of claim 7, wherein the firstcomplex number is determined also based on a cell identifier (cell ID).10. The UE of claim 7, wherein the circuitry is further configured to:determine another of the first set of orthogonal sequences; determine asecond complex number; and multiply another of the first set ofcomplex-valued symbols with an element of the another of the first setof orthogonal sequences and the second complex number to generate athird symbol, wherein: the second slot comprises a plurality of symbols,including the third symbol, and the second complex number is determinedbased on a slot number of the second slot and a symbol number of thethird symbol.
 11. The UE of claim 10, wherein the first complex numberand the second complex number has a same amplitude.
 12. The UE of claim8, wherein the one of the first set of orthogonal sequences isdetermined based on the index and Table 2 TABLE 2 Index First set oforthogonal sequences 0 [1 1 1 1 1] 1 [1 e^(j2π/5) e^(j4π/5) e^(j6π/5)e^(j8π/5)] 2 [1 e^(j4π/5) e^(j8π/5) e^(j12π/5) e^(j16π/5)] 3 [1e^(j6π/5) e^(j12π/5) e^(j18π/5) e^(j24π/5)] 4 [1 e^(j8π/5) e^(j16π/5)e^(j24π/5) e^(j32π/5)].


13. A communication device for a user equipment (UE), the communicationdevice comprising: circuitry which is configured to: cause the UE togenerate a set of bits based on retransmission information; cause the UEto generate a first set of complex-valued symbols based on the set ofbits; determine one of a first set of orthogonal sequences; determine afirst complex number; multiply one of the first set of complex-valuedsymbols with an element of the one of the first set of orthogonalsequences and the first complex number to generate a first symbol; causethe UE to generate a second symbol based on a reference signal sequence;cause the UE to generate a subframe comprising a first slot and a secondslot, wherein the first slot comprises a plurality of symbols, includingthe first symbol and the second symbol; and cause the UE to transmit thesubframe to a base station, wherein: the first complex number isdetermined based on a slot number of the first slot and a symbol numberof the first symbol.
 14. The communication device of claim 13, whereinthe circuitry is further configured to: determine an index, wherein theone of the first set of orthogonal sequences is determined based on theindex.
 15. The communication device of claim 13, wherein the firstcomplex number is determined also based on a cell identifier (cell ID).16. The communication device of claim 13, wherein the circuitry isfurther configured to: determine another of the first set of orthogonalsequences; determine a second complex number; and multiply another ofthe first set of complex-valued symbols with an element of the anotherof the first set of orthogonal sequences and the second complex numberto generate a third symbol, wherein: the second slot comprises aplurality of symbols, including the second symbol, and the secondcomplex number is determined based on a slot number of the second slotand a symbol number of the third symbol.
 17. The communication device ofclaim 16, wherein the first complex number and the second complex numberhas a same amplitude.
 18. The communication device of claim 14, whereinthe one of the first set of orthogonal sequences is determined based onthe index and Table 3 TABLE 3 Index First set of orthogonal sequences 0[1 1 1 1 1] 1 [1 e^(j2π/5) e^(j4π/5) e^(j6π/5) e^(j8π/5)] 2 [1 e^(j4π/5)e^(j8π/5) e^(j12π/5) e^(j16π/5)] 3 [1 e^(j6π/5) e^(j12π/5) e^(j18π/5)e^(j24π/5)] 4 [1 e^(j8π/5) e^(j16π/5) e^(j24π/5) e^(j32π/5)].